# People v. Peterson

> California Supreme Court · August 24, 2020 · 10 Cal. 5th 409

URL: https://www.frixlaw.com/law-library/cases/4558196

## Case

- **Court:** California Supreme Court
- **Decided:** August 24, 2020
- **Citations:** 10 Cal. 5th 409; 268 Cal. Rptr. 3d 56; 472 P.3d 382
- **Precedential status:** Published
- **Opinion:** Opinion
- **Cited by:** 76 later opinions in the Frix Law Library

## Citator (automated)

- No negative treatment found by the automated citator. That is not the same as a confirmation that the case is good law; read the citing cases.
- Full citator and citing cases: https://www.frixlaw.com/law-library/cases/4558196

## How later opinions describe it (automated extraction)

- concluding that 700,000 residents of San Mateo County constituted sufficiently large pool from which to draw jury in high profile death penalty case concerning husband who killed his preg- nant wife and unborn child

## Opinion text

IN THE SUPREME COURT OF
CALIFORNIA

THE PEOPLE,
Plaintiff and Respondent,
v.
SCOTT LEE PETERSON,
Defendant and Appellant.

S132449

San Mateo County Superior Court
SC55500

August 24, 2020

Justice Kruger authored the opinion of the Court, in which
Chief Justice Cantil-Sakauye and Justices Chin, Corrigan, Liu,
Cuéllar, and Groban concurred.
PEOPLE v. PETERSON
S132449

Opinion of the Court by Kruger, J.

A jury convicted defendant Scott Lee Peterson of one count
of first degree murder for killing his wife, Laci Peterson, and one
count of second degree murder for killing their unborn son. It
found true the special circumstance that Peterson had
committed multiple murders. At the penalty phase, the jury
returned a verdict of death. This appeal is automatic. (Pen.
Code, § 1239, subd. (b).)
Peterson contends his trial was flawed for multiple
reasons, beginning with the unusual amount of pretrial
publicity that surrounded the case. We reject Peterson’s claim
that he received an unfair trial as to guilt and thus affirm his
convictions for murder. But before the trial began, the trial
court made a series of clear and significant errors in jury
selection that, under long-standing United States Supreme
Court precedent, undermined Peterson’s right to an impartial
jury at the penalty phase. While a court may dismiss a
prospective juror as unqualified to sit on a capital case if the
juror’s views on capital punishment would substantially impair
his or her ability to follow the law, a juror may not be dismissed
merely because he or she has expressed opposition to the death
penalty as a general matter. (See Witherspoon v. Illinois (1968)
391 U.S. 510; Wainwright v. Witt (1985) 469 U.S. 412.) Here,
the trial court erroneously dismissed many prospective jurors
because of written questionnaire responses expressing
opposition to the death penalty, even though the jurors gave no
PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

indication that their views would prevent them from following
the law — and, indeed, specifically attested in their
questionnaire responses that they would have no such difficulty.
Under United States Supreme Court precedent, these errors
require us to reverse the death sentence in this case. (Gray v.
Mississippi (1987) 481 U.S. 648; see People v. Riccardi (2012) 54
Cal.4th 758, 778.) On remand, the People may retry the penalty
phase if they so choose.
I. FACTUAL AND PROCEDURAL BACKGROUND
A. Guilt Phase Trial
1. Prosecution Evidence
Peterson and Laci Rocha met in San Luis Obispo, where
Laci was attending college and Peterson was working in a
restaurant. They married in 1997. They opened and ran a
restaurant together in San Luis Obispo. In 2000, they moved to
Modesto and bought a house. Laci took a job as a substitute
teacher, while Peterson ran a start-up fertilizer company named
TradeCorp U.S.A. out of a leased warehouse. Some years after
the two married, Laci became pregnant; the baby — whom the
couple had named Conner — was due in February 2003.1
On December 23, 2002, Laci went grocery shopping
around midday. She also had a prenatal medical checkup. In
the late afternoon, both Laci and Peterson went to a salon where
Laci’s sister, Amy Rocha, worked. Amy mentioned that she had

1
For clarity, we generally will refer to Laci Peterson (neé
Rocha) and Conner by their first names. We will also sometimes
refer to members of Laci’s immediate family — her mother,
Sharon Rocha; her sister, Amy Rocha; and her brother, Brent
Rocha — by their first names. No disrespect is intended to any
of these individuals.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

ordered a gift basket for a family member that needed to be
picked up the next day by 3:00 p.m. Peterson volunteered to get
it for her, as he was going to be golfing nearby. Peterson also
invited Amy to dinner, but she declined because she had prior
plans. That night, Laci and her mother, Sharon, spoke on the
phone and confirmed that Laci and Peterson would join Sharon
and Sharon’s longtime partner, Ron Grantski, for dinner the
following night, Christmas Eve.
At 10:18 the following morning, a neighbor, Karen Servas,
saw the Petersons’ dog, McKenzie, wandering unaccompanied
on the street, wearing his leash. Peterson’s truck was gone;
Laci’s car was still in their driveway. There were no signs of
activity at the house, so Servas put McKenzie in the Petersons’
backyard and closed the gate. That afternoon, Grantski tried to
reach Laci, without success. Around 3:45 p.m., Amy received a
call that her gift basket had not been picked up. She was unable
to reach Peterson. Neighbors reported Peterson’s truck still
absent at 4:05 p.m., but back by 5:30 p.m.
At around 5:15 p.m., Peterson called Sharon and asked if
Laci was there. He described Laci as “missing.” Sharon
suggested he check with friends and neighbors. Peterson called
Sharon back shortly afterwards and reported the people he had
spoken to had not seen Laci either. Sharon told Grantski to call
the police. Officers soon met Peterson, Sharon, and Grantski at
a nearby park. Neighbors and other relatives gathered at the
park as well. Grantski spoke with Peterson and asked if he had
gone golfing that day. Peterson said he had changed his mind
and gone fishing instead. Told what time Peterson had gone,
Grantski suggested it was an unusually late time to be fishing.
Peterson walked off without responding. Peterson told a cousin
of Sharon’s and two neighbors that he had been golfing all day.
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

He volunteered to Sandy Rickard, a friend of Sharon’s, that he
would not be surprised if the police found blood in his truck
because he cut his hands all the time.
Police inspected the Peterson home. There were no signs
of forced entry, nothing appeared missing, and Laci’s purse was
still there. Peterson told officers he and Laci had watched
television that morning, and Laci had planned to walk the dog
and go grocery shopping. Peterson decided to go fishing in the
San Francisco Bay. He went to his company warehouse where
he stored a boat, drove to the Berkeley Marina, fished for two
hours, and quit because the day was cold and rainy. He tried
calling Laci on the home phone and her cell phone but did not
reach her. Peterson got home around 4:30 p.m. He washed his
clothes, ate some pizza, and then called Sharon to track down
Laci.
Officer Matthew Spurlock asked what time Peterson was
fishing. He also asked what Peterson was fishing for and what
lure he used. According to Spurlock and Officer Derrick
Letsinger, Peterson gave slow and initially noncommittal
answers. He “really didn’t give a responsive time” and, when
asked what he was fishing for, paused, gave a blank look, and
“mumbled some stuff” without really answering. Peterson
likewise responded with a blank look when asked about his lure,
but after some delay came up with a size and color description.
Detective Allen Brocchini was called to the Peterson home.
He found wet towels on top of the washing machine. Peterson
explained that he had taken them out so that he could wash the
clothes he had worn that day. Inside the washing machine were
Peterson’s jeans, shirt, and green pullover jacket. In the
bedroom, officers observed a laundry hamper nearly full of

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

clothes. With consent, Detective Brocchini examined Peterson’s
truck and saw large patio umbrellas and a tarp in the truck bed.
Inside the truck cab, he found a fishing rod and a bag containing
a package of unused fishing lures and a receipt indicating the
items had all been purchased on December 20. Peterson handed
him a Berkeley Marina parking receipt that indicated Peterson
had entered at 12:54 p.m. On the backseat was a camouflage
jacket Peterson said he had worn fishing that day. Brocchini
and Peterson then went to Peterson’s warehouse. There,
Brocchini observed what he described as a “homemade anchor”
made of concrete in Peterson’s boat, but no long rope to attach it
to the boat.
Peterson agreed to a further interview at the Modesto
police station. Peterson repeated that Laci had planned to walk
the dog and go grocery shopping. For his part, Peterson decided
to go fishing because it was too cold to golf. He went to his
warehouse, then to the Berkeley Marina around 1:00 p.m., and
fished for 90 minutes near an area that was later identified as
Brooks Island.2 Peterson did not pack a lunch or stop to eat on
the way to or from the marina. On the way back, Peterson called
Laci on their home phone and left two messages on her cell
phone.3 He dropped off his boat at the warehouse and went

2
Peterson said he left the house with no jacket on, put on a
green pullover jacket, and then put the camouflage jacket over
that when it started raining. The camouflage jacket, when
Detective Brocchini saw it in Peterson’s truck a few hours later,
was dry.
3
When messages on Laci’s cell phone were played, only one
voice message from Peterson was found.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

home. Peterson told officers that there were no problems in his
marriage.
Peterson had a followup interview with Detective Craig
Grogan and an investigator from the state’s Department of
Justice on Christmas Day, December 25. Peterson explained
that he had never fished on the San Francisco Bay before but
wanted to test out his boat. He troll fished4 for an hour on the
way out to Brooks Island from the marina dock. Peterson
suggested Laci might have been robbed of her jewelry by a
transient and then kidnapped. He denied being involved in an
affair with anyone. Later that day, Peterson called Detective
Brocchini to check on the investigation. He asked if the police
would be using cadaver dogs5 to search for Laci. Brocchini
explained that they would not, because no one assumed Laci was
dead.
In the days after Christmas, the Modesto Police
Department executed search warrants on the Peterson home
and Peterson’s warehouse. Police confirmed that there had been
no forced entry at the house. None of Laci’s jewelry was missing,
other than one pair of diamond earrings. Traces of Peterson’s
blood were found on a comforter in the master bedroom. In
sheds in the backyard, police found the cover to Peterson’s boat,
smelling heavily of gasoline,6 as well as a blue tarp. The boat
cover had chunks of concrete in it. In Peterson’s truck, police

4
Troll fishing involves dragging a baited line through the
water.
5
Cadaver dogs are trained to scent and alert to
decomposing human remains.
6
At trial, evidence was introduced that gasoline makes it
extremely difficult for trailing dogs to identify a human scent.

6
PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

found additional spots of Peterson’s blood. Peterson explained
that he had cut his hand on the truck door. Police found small
chunks of cement and a claw hammer with cement powder on it
in the truck’s bed.
At the warehouse, the police inspected the boat and found
a pair of pliers under the middle seat. The pliers had hair
clamped in their teeth. Subsequent mitochondrial DNA testing
of a hair fragment determined that the hair matched a reference
sample from Sharon, which meant that its donor had the same
maternal lineage as Sharon. The hair did not match Peterson’s.
During the search of the Peterson home, articles that Laci
would have touched were collected to give to trailing dogs to
enable them to search for Laci’s scent. These included a slipper
and a pair of sunglasses. On December 28, four days after Laci
disappeared, Trimble, a trailing dog, was presented Laci’s
sunglasses at the Berkeley Marina. Trimble alerted to Laci’s
scent along a path that led out onto a dock and ended at the
water.
On December 30, a woman named Amber Frey contacted
the police after a friend advised her that Peterson, who she
thought was unmarried with no children, and with whom she
had been having a relationship since November, was connected
to the disappearance of his pregnant wife. Frey and Peterson
had had their first date on November 20 and had immediately
become sexually intimate. Their relationship had progressed to
the point where Peterson had stayed over at Frey’s home, picked
up Frey’s young daughter from daycare, gone to various parties
with Frey, alone and with her daughter, picked out a Christmas
tree with Frey, and discussed their views on having children.
Peterson initially told Frey he had never been married and had

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

no children, but on December 6 a friend of Frey’s discovered
otherwise and gave him an ultimatum to tell Frey by December
9 or else she would. On December 9, Peterson explained to Frey
that he had in fact been married, but had “lost” his wife, and the
upcoming holidays would be his first without her. On December
15, Peterson told Frey he would be in Europe on business
through the rest of the month and much of January. On
December 23, after Frey asked where she should send him
things while he was away, Peterson rented a private mailbox to
which Frey could send letters. He called Frey that day, claiming
to be in Maine duck hunting with his father, and again on
Christmas Day, supposedly still from Maine.
After meeting with police, Frey agreed to cooperate and
tape future calls from Peterson. On New Year’s Eve, Peterson
called Frey from a vigil for Laci, claiming to be in Paris watching
fireworks over the Eiffel Tower. He called Frey again on New
Year’s Day and in the days after, maintaining the fiction that he
was in Europe. On January 3, 2003, when police confronted
Peterson with a picture of himself and Frey, Peterson denied
that it was him in the photo and that he was having an affair.
On January 6, at the instigation of police, Frey dropped
hints that a friend had learned the truth and would tell her in a
matter of hours.7 In response, Peterson finally admitted to Frey
that he was married to a woman named Laci and had been in
Modesto the entire time. The next day, when Frey asked if
Peterson had told Laci about her, Peterson said he had and that

7
Laci’s disappearance swiftly became the subject of
widespread media attention. To maintain the pretense that she
did not know the truth about Peterson yet, Frey denied watching
the news.

8
PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

Laci was “fine” with his having an affair. Later in the month,
once news media had made the affair public, Peterson, in an
interview aired nationwide, repeated that Laci was fine with his
having an affair and said he had disclosed the affair to the police
immediately. On February 19, at the direction of police
investigators, Frey told Peterson they should stop talking.
In January, after obtaining a warrant, police placed a
surveillance camera outside the Peterson home and GPS
tracking devices on Peterson’s vehicles, including a series of cars
and trucks Peterson rented for a few days at a time.
Surveillance data from these devices and visual surveillance by
the police showed Peterson driving the approximately 90 miles
from his home to the Berkeley Marina at least five times in
January, each time using a different vehicle. On January 5, he
drove there in a gray Subaru, spent five or ten minutes, and left.
On January 6, he returned to the marina in a red Honda and
again spent only a few minutes. On January 9, Peterson drove
there in a white pickup truck. On January 11, after determining
that their cover had been blown, the Modesto Police Department
shut down surveillance at the Peterson home. Nonetheless,
from tracking data supplied by the automobiles’ manufacturers,
police were able to determine that Peterson returned to the
marina on January 26 in Laci’s Land Rover and on January 27
in a rented Dodge Dakota.
During the same period, Peterson began to make various
changes to his work and living situations. On January 13,
Peterson gave 30 days’ notice that he was terminating his
warehouse lease, which was not up until October. That same
month, he started discussions to sell the Peterson home. On
January 29, Peterson sold Laci’s car, trading it in for a Dodge
Dakota pickup truck. On January 30, he stopped home mail
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

delivery and directed that all mail be delivered to the post office
box he had set up on December 23. The nursery for Conner was
converted into storage space. On February 18, satellite
television service to the Peterson home was canceled; the
satellite company’s records indicated the customer had
explained he was moving overseas.
A $500,000 reward was posted by a private foundation for
information leading to Laci’s return. For months, no useful
leads turned up. Even when potentially promising sightings
were reported, Peterson appeared to show little interest. For
example, the prosecution presented evidence collected from an
authorized wiretap of Peterson’s phone that showed he took
days to follow up with police about a possible sighting in
Washington, though he told others — including his mother —
that he had followed up with police immediately. Peterson
similarly told a business associate he was waiting near the
airport in case he needed to fly up to Washington, though at the
time, Peterson was not near any airport.
In mid-April, a significant storm hit the San Francisco Bay
Area. On April 13, after the storm had passed, a couple walking
their dog came upon Conner’s badly decomposed body,
apparently washed ashore along with other storm debris. The
location was just over a mile from the southern tip of Brooks
Island. The next morning, Laci’s body was discovered on the
shoreline at Point Isabel, south of Conner’s body and again just
over a mile from Brooks Island. Laci’s body had barnacles and
duct tape on it. From residual clumps of fabric, it was possible
to determine that she had been wearing light-colored capris.
The clothing was consistent with the recollection of Amy, who
testified that Laci was wearing cream-colored pants when she
last saw her sister on December 23. It was, however,
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

inconsistent with the recollection of Peterson, who told police
that Laci was wearing black pants when he last saw her on
December 24. Days later, DNA testing confirmed the identities
of the two bodies.
Dr. Brian Peterson (no relation to the Petersons)
performed autopsies on both bodies. Laci’s body had several
parts missing, including her head, forearms, and one lower leg.
Changes to the tissue suggested her body had been in a marine
environment. Tidal action and marine animals could explain
the missing body parts. Laci’s uterus was still enlarged, her
birth canal was closed, and there was no evidence of a
Caesarian-section birth, which indicated she had died while still
pregnant. Dr. Allison Galloway, a forensic anthropologist given
the remains to analyze, testified that Laci had been in water for
three to six months. Given the condition of the body, it was not
possible to determine a cause of death.
Conner’s body was intact. There was tape on his neck but
no associated injuries, which led Dr. Peterson to conclude the
tape was just debris that had become attached to Conner after
his death. There was no clothing on the body. Conner still had
part of his umbilical cord and meconium in his intestines, which
indicated he had died before birth. Based on his size and the
softness of his tissue, Dr. Peterson opined that Conner must
have remained protected inside Laci’s uterus for some time after
death; had he spent a significant period of time exposed in the
water, he would have been eaten by marine animals.
As mentioned, Laci had had a prenatal checkup on
December 23. Based on ultrasounds, Conner was at 32 to 33
weeks of gestation. Post-mortem measurements of his bone
growth allowed Dr. Greggory DeVore to estimate Conner’s date

11
PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

of death as falling between December 21 and December 24, with
an average of December 23. Both Dr. Esther Towder, Laci’s
gynecologist who conducted the December 23 checkup, and
Dr. Peterson testified that based on his age and health, Conner
would have survived had he been born that day.
Dr. Ralph Cheng, a hydrologist with the United States
Geological Survey, was contacted by the Modesto Police
Department in February, while Laci was still missing, and again
in May, after she and Conner had been found. The first time, he
was asked to assume that Laci’s body had been dumped with
weights into the San Francisco Bay and, based on that
assumption, to estimate where the body might be found. The
second time, after the bodies had been found, Dr. Cheng was
asked to estimate where they might have originated. He was
able to estimate a location for Conner near the southern tip of
Brooks Island, but no likely location for Laci. Divers searching
the bay at Dr. Cheng’s target location were unable to find any
relevant evidence.
On April 12, the day before Conner’s body was found,
Peterson bought a car using his mother’s name, Jacqueline, as
his own, providing a fake driver’s license number, and paying
$3,600 in cash. He had grown a goatee and mustache and
appeared to have dyed his hair. On April 15, when Sharon
called him about the discovery of the (as-yet unidentified) bodies
of Conner and Laci, Peterson did not return her call. Believing
Peterson might flee, police arrested him on April 18. When
arrested, Peterson had nearly $15,000 in cash, foreign currency,
two drivers’ licenses (his own and his brother’s), a family
member’s credit card, camping gear, considerable extra clothing,
and multiple cell phones.

12
PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

The prosecution introduced evidence concerning the
Petersons’ finances. The Petersons’ expenses were high in
relation to their current income. TradeCorp U.S.A. had never
been profitable, posting operating losses of $40,000 and
$200,000 in consecutive years; the company was not meeting
sales goals, and it owed its parent company $190,000. Peterson
had signed multiple credit card applications in the company’s
name containing misrepresentations as to the company’s
income.
In fall 2002, Laci inherited jewelry and, at Peterson’s
request, had some of the items appraised. They were valued at
more than $100,000. Computers seized from the Peterson home
and the warehouse showed e-mails sent from an account bearing
the username “slpete1” discussing the sale of jewelry, and eBay
records likewise showed Peterson had posted jewelry items for
sale. Laci also stood to inherit one-third of the proceeds from
the sale of her grandfather’s house, an interest estimated to be
worth around $140,000. Laci’s interest would terminate on her
death, with no right of survivorship to Peterson, but it was
unclear whether Peterson was aware of the limitation; Brent,
the cotrustee of the grandparents’ estate, had not told Peterson
about the provision.
The prosecution also submitted additional background
concerning Peterson’s fishing. Computers seized from the
Peterson home and the warehouse showed that someone had
conducted searches of classified advertisements for boats on
December 7, the day after Peterson learned he would no longer
be able to conceal his marriage from Frey. That same day,
Peterson called Bruce Peterson (no relation) about a boat for
sale. Peterson inspected the boat the next day and bought it on
December 9, without the anchors that came with the boat.
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Opinion of the Court by Kruger, J.

Peterson never registered the boat, nor did he ever mention the
purchase to his father; to Grantski, an avid fisherman who had
invited Peterson to fish several times; to other members of the
Rocha family; or to his friend Gregory Reed, with whom he
frequently discussed fishing. Review of the seized computers’
browser histories also showed someone conducting searches on
December 8 for boat ramps on the Pacific Ocean, then examining
nautical charts, currents, and maps for the Berkeley Marina and
San Francisco Bay, including the area around Brooks Island.
There were also visits to fishing-related websites.
December 24, the day Peterson said he was fishing, was
gray, damp, and cold with a bit of wind. Few people were at the
Berkeley Marina. When questioned by police, Peterson would
not say what he was hoping to catch, but the fishing searches
performed from his computer earlier in the month had included
searches relating to sturgeon and striped bass. Angelo
Cuanang, a published author on fishing in the San Francisco
Bay who was accepted by the court as an expert fisherman,
testified that Brooks Island was the wrong place to seek
sturgeon, which congregated in a different part of the bay that
time of year. Sturgeon also preferred live bait to lures, and
Peterson’s rod was too weak to catch them. Anchoring was
essential to reel in sturgeon; the homemade cement anchor in
his boat would have been inadequate. Finally, it was illegal to
troll for sturgeon, as Peterson claimed to have done. Peterson’s
lures and the time of year he was fishing were also wrong for
catching striped bass.
The prosecution’s theory was as follows: Peterson killed
Laci sometime on the night of December 23 or morning of
December 24. On the morning of the 24th, Peterson let their
dog McKenzie out with his leash on to make it appear something
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Opinion of the Court by Kruger, J.

had happened while Laci was walking him. He wrapped Laci’s
body in a tarp in the bed of his truck, covered her with the patio
umbrellas, drove to the warehouse, and then moved her body
into his boat.8 He drove to the Berkeley Marina, motored out to
an area near Brooks Island, and slipped her body, attached to
homemade concrete weights like the homemade anchor
Peterson had made, into the bay.9 Peterson then returned to
Modesto, dropped off the boat at the warehouse, put the boat
cover out back under a leaky gas blower so that any scent would
be obscured, washed his clothes, and proceeded with the ruse
that Laci was missing, hoping her body would never be
discovered.
2. Defense Evidence
The defense argued the police had not diligently pursued
whether a person or persons other than Peterson were more
likely responsible for Laci’s disappearance and murder. The
defense presented evidence that a burglary had occurred on the
Petersons’ street the week of her disappearance and argued that
the police failed adequately to follow up on whether that
burglary had any connection to Laci’s disappearance. It also
presented evidence that a stranger had gone to several houses
on December 23 asking for money and, one neighbor thought,
casing houses for burglaries, and so might have had something
to do with her disappearance. Testimony was presented that

8
The prosecution introduced photographs of a district
attorney’s office employee, at approximately the same stage of
pregnancy and weight as Laci at her disappearance, fitting into
the bottom of Peterson’s boat.
9
Through an engineer for the company that manufactured
the boat, the prosecution introduced stability tests the boat
model underwent to obtain certification before it was sold.

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Opinion of the Court by Kruger, J.

the same neighbor, walking with a police officer on Christmas
Day to look for the stranger, had seen a pair of sandals lying in
the road 150 feet from the Petersons’ home; the neighbor
wondered at the time if they might have any connection to Laci’s
disappearance, but the officer just left them there. To support
the possibility of a third party’s involvement, the defense
challenged the prosecution’s theory that Conner died December
23 or 24, presenting its own expert who testified based on
ultrasounds and other evidence that Conner lived until after
Christmas.
The defense also sought to challenge other aspects of the
prosecution’s case. To rebut the dog-trailing evidence, the
defense called Ronald Seitz, a second dog handler who also had
his dog try to find Laci’s scent at the Berkeley Marina on
December 28. The dog, T.J., was given Laci’s slipper as a scent
object, but discovered no scent trail. To rebut the inference that
Peterson had a financial incentive to kill Laci, the defense
presented a financial expert who testified that TradeCorp
U.S.A. and the Petersons were both reasonably financially
healthy. To portray the prosecution’s theory as physically
impossible, the defense also sought to introduce video of a
demonstration with a weighted 150-pound dummy in a boat on
the bay in which a defense firm employee, trying to dump the
dummy out, sank the boat. As will be discussed below, the trial
court excluded the video.
The defense offered explanations for the circumstances of
Peterson’s behavior in April. His use of his mother’s name to
purchase a car was at her suggestion, to avoid having it
impounded. He had large amounts of cash because she gave it
to him to reimburse him for money erroneously withdrawn from
his bank account rather than hers. Finally, he had his brother’s
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Opinion of the Court by Kruger, J.

driver’s license because the club where he was going to golf that
day gave discounts for local residents such as his brother.
3. Guilt Phase Verdict
The jury found Peterson guilty of murder in the first
degree for killing Laci and murder in the second degree for
killing Conner. (See Pen. Code, §§ 187, 189.) It found true the
sole charged special circumstance, for multiple murder. (See id.,
§ 190.2, subd. (a)(3).)
B. Penalty Phase Trial
1. Prosecution Evidence
Peterson had no criminal record nor any history of violent
acts. At the penalty phase, the prosecution relied exclusively on
the circumstances of the crime and victim impact evidence.
Four members of Laci’s immediate family — her mother,
Sharon; her stepfather, Ron Grantski; her brother, Brent; and
her sister, Amy — testified. They described who Laci was as a
person, shared photographs, memories, and vignettes from her
life, and conveyed the grief and loss they each felt after the
deaths of Laci and her unborn child.
2. Defense Evidence
Through friends, family, neighbors, teachers, coworkers,
employers, and other witnesses, the defense offered evidence
that Peterson had been a kind and positive member of the
community. Peterson grew up in a loving family, displayed a
patient and gentle disposition, and was a solid student. As part
of his high school community service requirement, Peterson
worked at a home for the elderly and tutored homeless children.
He started his own business and worked a variety of other jobs
while in college.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

According to the defense, Peterson was always calm with
Laci. Indeed, witnesses testified Peterson was calm at all
times — at work, on the golf course, and in his dealings with all
those around him.
Friends and family testified to the impact the trial had
had on Peterson’s relatives and indicated they believed, if
sentenced to life in prison, Peterson could make a positive
impact on the lives of others.
In closing argument, defense counsel described Peterson’s
life as one worth saving and argued that lingering doubt about
Peterson’s guilt should also weigh in favor of a life verdict.
3. Penalty Phase Verdict and Sentence
The jury returned a death verdict. The court denied a
motion for new trial, denied the automatic motion for
modification of the verdict, and imposed a sentence of death.
II. DISCUSSION
A. Excusal of Prospective Jurors for Cause Based
on Questionnaire Answers Reflecting
Opposition to the Death Penalty
Peterson claims errors occurred during every phase of his
trial. We begin with his challenge to the manner in which the
jury was chosen. During jury selection, multiple prospective
jurors were excused based solely on written questionnaire
responses indicating they were personally opposed to the death
penalty. Peterson contends that, absent any indication these
jurors would be unable to faithfully and impartially apply the
law, it was error to remove them from the juror pool.
On this initial point, Peterson is correct. Long-standing
United States Supreme Court precedent makes clear that
prospective jurors may not be disqualified from service in a

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

capital case solely because of their general objections to the
death penalty. (See Witherspoon v. Illinois, supra, 391 U.S. at
pp. 518–523 (Witherspoon); Wainwright v. Witt, supra, 469 U.S.
at p. 424 (Witt).) That is just what happened here. And as this
court has repeatedly explained, under high court precedent,
even one such error requires “automatic reversal of any ensuing
death penalty judgment.” (People v. Heard (2003) 31 Cal.4th
946, 966–967; accord, e.g., People v. Armstrong (2019) 6 Cal.5th
735, 764; People v. Woodruff (2018) 5 Cal.5th 697, 745; People v.
Riccardi, supra, 54 Cal.4th at p. 783.) Here, there was not just
one error; there were many. We are therefore required to
reverse the death judgment. Contrary to Peterson’s argument,
however, we are not also required to reverse the judgment of
guilt.
Jury selection in a capital case typically begins with
prospective jurors filling out written questionnaires. These
questionnaires allow the court and counsel to explore potential
jurors’ views and past experiences that might affect how they
evaluate the evidence to be presented. They also address views
a juror might have concerning the death penalty, in the event a
defendant is found guilty and findings are made that would
render him or her eligible to be punished by death. The
questionnaire in this case, based on proposals from the parties
and as approved by the court, contained roughly 120 questions
on a range of topics, including 13 directed to potential jurors’
views on the death penalty. To supplement the picture painted
by answers to written questionnaires, the court and counsel may
ask prospective jurors individual questions orally to clarify the
nature of any views and further evaluate their ability to serve,
a process known as voir dire. (See People v. Armstrong, supra,

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Opinion of the Court by Kruger, J.

6 Cal.5th at p. 749; Hovey v. Superior Court (1980) 28 Cal.3d 1,
80–81.)
Prospective jurors may be excused from jury service
through one of two primary mechanisms. First, the court may
excuse jurors for cause based on a determination that bias or
another substantial impairment disqualifies them from service.
In a capital case, prospective jurors are subject to excusal if they
would be unable or unwilling to impose the death penalty (or,
conversely, if they would be unable or unwilling to vote against
death) should the defendant be found guilty. (See, e.g., Ross v.
Oklahoma (1988) 487 U.S. 81, 83–86; Lockett v. Ohio (1978) 438
U.S. 586, 595–596.) Second, prospective jurors may be excused
by the parties by means of peremptory challenge. Each party is
given a number of peremptory strikes set by law and allowed to
cull from the remaining pool, up to the limit of their strikes,
additional potential jurors they believe would be less favorably
disposed to their side and to the verdict they seek. The result of
this process is a final jury of 12, plus alternates to guard against
the need to excuse one or more jurors during trial itself.
We are concerned here only with the first mechanism,
excusal for cause. The question is whether the process the trial
court employed to remove jurors complied with the standards
the United States Supreme Court has established for the
disqualification of jurors for bias in a capital case.
More than half a century ago, the United States Supreme
Court held in Witherspoon, supra, 391 U.S. at page 522, that “a
sentence of death cannot be carried out if the jury that imposed
or recommended it was chosen by excluding veniremen for cause
simply because they voiced general objections to the death
penalty or expressed conscientious or religious scruples against

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

its infliction.” The court explained the reason for this rule: “A
man who opposes the death penalty, no less than one who favors
it, can make the discretionary judgment entrusted to him by the
State and can thus obey the oath he takes as a juror. But a jury
from which all such men have been excluded cannot perform the
task demanded of it,” namely, to “express the conscience of the
community on the ultimate question of life or death.” (Id. at
p. 519.) Put differently, “a criminal defendant has the right to
an impartial jury drawn from a venire that has not been tilted
in favor of capital punishment by selective prosecutorial
challenges for cause” based solely on general opposition to the
death penalty. (Uttecht v. Brown (2007) 551 U.S. 1, 9.)
The law also recognizes, however, that states must have a
way to ensure capital cases are tried before juries “able to apply
capital punishment within the framework state law prescribes.”
(Uttecht v. Brown, supra, 551 U.S. at p. 9.) In Witt, supra, 469
U.S. 412, the court held that trial courts may excuse a
prospective juror for cause based on the juror’s views of capital
punishment if those views “would ‘prevent or substantially
impair the performance of his duties as a juror in accordance
with his instructions and his oath.’ ” (Id. at p. 424, quoting
Adams v. Texas (1980) 448 U.S. 38, 45; accord, People v. Jones
(2017) 3 Cal.5th 583, 614.) But to protect the right to trial by
impartial jury, a trial court may not remove jurors for cause
based on views that do not substantially impair their ability to
serve. “[I]f prospective jurors are barred from jury service
because of their views about capital punishment on ‘any broader
basis’ than inability to follow the law or abide by their oaths, the
death sentence cannot be carried out.” (Adams, at p. 48; accord,
Uttecht, at p. 9; Jones, at p. 614.)

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Opinion of the Court by Kruger, J.

Taken together, Witherspoon and Witt make clear that
prospective jurors may not be disqualified from service simply
because they object to the death penalty as a general matter.
“[N]ot all who oppose the death penalty are subject to removal
for cause in capital cases; those who firmly believe that the
death penalty is unjust may nevertheless serve as jurors in
capital cases so long as they state clearly that they are willing
to temporarily set aside their own beliefs in deference to the rule
of law.” (Lockhart v. McCree (1986) 476 U.S. 162, 176.) Nor may
a juror be disqualified from service because he or she might
“impose a higher threshold before concluding that the death
penalty is appropriate.” (People v. Stewart (2004) 33 Cal.4th
425, 447.) “The critical issue is whether a life-leaning
prospective juror — that is, one generally (but not invariably)
favoring life in prison instead of the death penalty as an
appropriate punishment — can set aside his or her personal
views about capital punishment and follow the law as the trial
judge instructs.” (People v. Thompson (2016) 1 Cal.5th 1043,
1065.) If a juror can obey those instructions and determine
whether death is appropriate based on a sincere consideration
of aggravating and mitigating circumstances, the juror may not
be excused for cause. (People v. Armstrong, supra, 6 Cal.5th at
p. 750; Stewart, at p. 447; People v. Lewis (2001) 25 Cal.4th 610,
633.)
Here, Peterson directs our attention to a group of
prospective jurors who were excused based solely on their
questionnaire answers, without further questioning by the court
or counsel. When dismissal is based solely on the written record,
we independently review whether that record establishes that a
juror was categorically unable to serve. (People v. Woodruff,
supra, 5 Cal.5th at p. 743; People v. Riccardi, supra, 54 Cal.4th

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Opinion of the Court by Kruger, J.

at p. 779.) “ ‘[W]hen an excusal was based on questionnaire
responses alone, the excusal may be upheld if those answers,
“taken together,” clearly demonstrate the juror’s unwillingness
or inability, because of attitudes about the death penalty, to
perform his or her duties in a capital trial.’ ” (Riccardi, at
p. 779.)
The record reveals that many jurors were summarily
excused based on their responses to a single question, No. 109:
“How would you rate your attitude towards the death penalty?”
That question gave prospective jurors six possible answers —
Strongly Oppose, Oppose, Weakly Oppose, Weakly Support,
Support, and Strongly Support — and spaces to mark which one
of these most closely reflected their general attitude. Although
the prospective jurors’ answers to this question could well have
prompted further inquiry during voir dire, these answers alone
offered little insight into the controlling issue for purposes of
their qualification to serve as jurors — whether they, whatever
their general views on the death penalty might be, could accept
and follow the court’s instructions and be able to choose either
life or death based on a sincere consideration of any aggravating
or mitigating circumstances. (People v. Armstrong, supra, 6
Cal.5th at p. 750.) On that issue, a second question, No. 115,
was more illuminating. It asked: “Do you have any moral,
religious, or philosophical opposition to the death penalty so
strong that you would be unable to impose the death penalty
regardless of the facts?”10

10
A related question, No. 116, screened for jurors on the
other end of the spectrum. It asked: “Do you have any moral,
religious, or philosophical beliefs in favor of the death penalty

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

Peterson asks us to focus in particular on 13 prospective
jurors who were excused without further questioning after
expressing some degree of opposition to the death penalty in
response to question No. 109, even though these same jurors
also answered “no” to question No. 115 — meaning that, so far
as their questionnaires revealed, none held views so strong that
they would be unable to vote for death if the circumstances
warranted. The trial court dismissed these 13 prospective jurors
as not qualified to serve without, insofar as the record reveals,
ever probing their views on the ultimate issue, whether they
were substantially impaired.
Take, for example, Prospective Juror No. 4841. Asked in
her questionnaire her feelings toward the death penalty, the
juror wrote: “Have no feeling.” Two questions later, asked to
rate her attitude toward the death penalty and given the
aforementioned range of options from “Strongly Oppose” to
“Strongly Support,” she checked “Strongly Oppose.” But in
response to the additional question, “Do you have any moral,
religious, or philosophical opposition to the death penalty so
strong that you would be unable to impose the death penalty
regardless of the facts?” (italics added), the prospective juror
checked “No.” Indeed, the juror implicitly confirmed that in
some instances she could impose the death penalty; asked
whether it would “be difficult for you to vote for the death
penalty if the crime was the guilty party’s first offense?,” she
checked “No.”
Discussing the juror and whether counsel would stipulate
to her excusal, the court said: “Reading these [questionnaire

so strong that you would be unable to impose life without
possibility of parole regardless of the facts?” (Italics added.)

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

answers], I am of the opinion this juror wouldn’t qualify. [¶]
Look at 4841. Go to that one. 19 — page 19, answer 109.
Strongly opposes the death penalty. I could dispose of this juror
in a couple of questions. So if you don’t want to stipulate, fine.
But if they oppose the death penalty, they are not qualified
under Wainwright [v.] Witt.” That afternoon, the trial court
read off the juror’s answer to the attitude question, No. 109,
again noting that she had checked, “Strongly Opposed.” On that
basis, he concluded “this juror . . . would not qualify” and
excused her without any questioning.
In response to these same questions, Prospective Juror
No. 6960 said of the death penalty, “I wish it was not a thing
needed” and checked that she opposed (not that she strongly
opposed) the death penalty. But she too indicated on the very
next page that her opposition to the death penalty was not such
as would render her “unable to impose the death penalty
regardless of the facts.” Based on these answers, the court
described the juror as “one who is opposed to the death penalty
without qualification” and concluded it would “excuse 6960 for
cause, because that juror is opposed to the death penalty,
without reservation.”
Prospective Juror No. 16727 indicated he was strongly
opposed to the death penalty based on his “spirituality,” but his
opposition was not such that he could never impose it no matter
the facts. His questionnaire indicated that, if the crime was a
defendant’s first offense, whether it would be difficult to vote for
death would “[d]epend[] on the [e]vidence” — implying the juror
could, in some instances, vote for death even for a first-time
offender. The trial court, noting that the juror wrote he was
“against the death penalty” and checked that he “strongly
oppose[d]” it, said, “I don’t think this person would qualify
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

because of his answers, and he’s opposed to the death penalty.
So I would be inclined to excuse him. Over the objection of
[defense counsel].” After defense counsel confirmed his
“vehement objection,” the court excused the juror without
questioning him: “[J]uror number 16727 is excused because he
is opposed to the death penalty.”
Again, these were not isolated occurrences. The trial court
excused more than a dozen prospective jurors based solely on
their written opposition to the death penalty (question No. 109),
without also considering their answers to question No. 115,
which reflected the jurors’ ability to impose the death penalty in
some circumstances. Perhaps further questioning might have
established that one or more of these jurors in truth could not
conscientiously consider death as an option. But no such
questioning occurred here, because the trial court rejected
counsel’s requests to question these prospective jurors and
declined to ask any questions itself. As a result, these jurors
were excused for cause based on a written expression of
opposition to the death penalty, without more.
We do not suggest that a trial court errs any time it
exercises its discretion to limit counsel’s opportunity to question
prospective jurors directly. In a case with a venire of this size —
nearly 1,500 prospective jurors — tight controls on voir dire
were necessary and inevitable. But a court must still ensure
that, by whatever means, sufficient inquiry is made so only
those properly excusable under the governing standards are
dismissed for cause: “ ‘Before granting a challenge for cause, the
“court must have sufficient information regarding the
prospective juror’s state of mind to permit a reliable
determination as to whether the juror’s views would ‘ “prevent
or substantially impair” ’ ” performance as a capital juror.
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

[Citation.] Trial courts must therefore make “a conscientious
attempt to determine a prospective juror’s views regarding
capital punishment to ensure that any juror excused from jury
service meets the constitutional standard.” ’ ” (People v.
Buenrostro (2018) 6 Cal.5th 367, 412.) Sufficient inquiries were
not made in this case.
The People concede Peterson’s claims are all preserved
because at the time of trial no objection was required to preserve
claims of Witt/Witherspoon error. (See People v. Jones (2013) 57
Cal.4th 899, 914–915 [describing evolution of the forfeiture rule
for such error].) In any event, the record shows defense counsel
consistently resisted these dismissals, arguing on numerous
occasions that just because a juror indicated opposition to the
death penalty, that did not mean he or she could not vote for
death in appropriate circumstances. These objections gained no
traction with the trial court, and ultimately the defense had no
choice but to accede to the for-cause standard the court had
adopted: “Obviously[,] I believe that opposition to the death
penalty should not be a for-cause challenge. The Court has ruled
on it. I’m not going to continue to raise it each time. Although
I want the record to reflect that I am submitting [subject to a
standing objection] on the Court’s previous rulings.”
Crucially, “it is the adversary seeking exclusion who must
demonstrate, through questioning, that the potential juror lacks
impartiality.” (Witt, supra, 469 U.S. at p. 423; accord, People v.
Stewart, supra, 33 Cal.4th at p. 445.) It is thus incumbent on
the party seeking excusal, or the court, to ask questions
sufficient to differentiate between mere opposition and an actual
inability to impose the death penalty. The exclusion of
prospective jurors as impaired, in the absence of a record
demonstrating they were impaired, is a violation of the Sixth
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

Amendment right to an impartial jury. (See People v. Woodruff,
supra, 5 Cal.5th at pp. 744–745 [error not to ask clarifying
questions to determine whether written indication of opposition
to the death penalty would impair juror’s ability to serve]; People
v. Riccardi, supra, 54 Cal.4th at p. 782 [same]; Stewart, at
pp. 449–452 [same].)
Even though neither the court nor the prosecution
questioned these 13 excused jurors, the People argue that all 13
dismissals are supported by substantial evidence in the record.
Given the absence of questioning, the People rely solely on the
jurors’ questionnaire responses. In addition to the opposition to
the death penalty reflected in the jurors’ answers to question
No. 109, the People point to other responses to questions about
the jurors’ death penalty attitudes — for example, that in many
cases their views had not changed in the last 10 years, or that
some jurors anticipated it would be difficult for them to choose
death for a first-time offender.
There are two difficulties with the People’s response. The
first is that it misstates the standard of review; as discussed,
when dismissal for cause based on an inability to impose the
death penalty rests solely on written questionnaire answers, we
review the record de novo, rather than under the deferential
substantial evidence standard. (People v. Woodruff, supra, 5
Cal.5th at p. 743.) The second, more fundamental difficulty is
that nothing in the prospective jurors’ questionnaire responses
establishes that the jurors would have been unable to follow the
law and impose the death penalty if circumstances warranted,
which is the only relevant question under high court precedent.
There is no dispute that each of the 13 prospective jurors
opposed the death penalty, sometimes strongly so. But the issue
is whether that opposition would have disabled them from
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

following the court’s instructions and ever imposing the death
penalty. On that point, in response to question No. 115, all 13
prospective jurors expressly indicated their death penalty views
were not so strong that they would be unable to impose the
death penalty. That answer required further inquiry before the
court could conclude these jurors were impaired. (See People v.
Leon (2015) 61 Cal.4th 569, 592–593.)
In sum: The law is clear that a capital jury may include
those who, as an abstract matter, oppose — or even strongly
oppose — the death penalty, though a prosecutor might seek to
limit the number of such jurors. It may include those who
favor — or even strongly favor — the death penalty, though
defense counsel might seek to limit their numbers. Eligibility
for service does not depend on a juror’s abstract views of capital
punishment. It depends, instead, on the prospective juror’s
willingness and ability to follow a court’s instructions and
conscientiously consider both penalties in light of the evidence
presented by each side. This is the meaning of the guarantee of
an impartial jury, drawn from the community at large, for the
trial of a defendant facing the death penalty.
Under that standard, the questionnaire answers
submitted by these prospective jurors did not establish they
were unfit to serve. Voir dire might have painted a different
picture, with the court and counsel through oral questions
exploring whether each individual juror had the necessary
ability and willingness to consider both life and death as options.
But for these 13 jurors, there was no such questioning. Thus,
we know only that in the abstract they opposed the death
penalty. The record made in the trial court does not offer a basis
sufficient to uphold excusal of these jurors for cause under the
clear standards laid out by the United States Supreme Court.
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

The People contend these errors in jury selection should
be treated as harmless. But precedent requires otherwise.
Witherspoon itself held “that a sentence of death cannot be
carried out” if it has been imposed by a jury chosen after
disqualifying prospective jurors for having “voiced general
objections to the death penalty.” (Witherspoon, supra, 391 U.S.
at p. 522.) The United States Supreme Court has since
instructed that even a single erroneous exclusion of a
prospective juror based solely on his or her general views about
the death penalty requires that any death sentence thereafter
imposed be set aside. (Gray v. Mississippi, supra, 481 U.S. at
p. 665 (plur. opn. of Blackmun, J.) [“The nature of the jury
selection process defies any attempt to establish that an
erroneous Witherspoon-Witt exclusion of a juror is harmless”];
see id. at p. 672 (conc. opn. of Powell, J.); see People v. Riccardi,
supra, 54 Cal.4th at p. 778 [Witherspoon-Witt error “requires
automatic reversal of defendant’s sentence of death under
existing United States Supreme Court precedent”].) Here, the
trial court excluded no fewer than 13 jurors based on their
general views about the death penalty, even though all 13
attested that their views would not prevent them from following
the law. The death sentence must be reversed, and the People
given another opportunity to seek that penalty before a properly
selected jury if they so choose.
In their brief, the People asked us to reconsider our cases,
including principally People v. Riccardi, supra, 54 Cal.4th 758,
that hold the erroneous exclusion of a juror based on death
penalty views can never be harmless. But at oral argument, the
People acknowledged that Gray v. Mississippi, supra, 481 U.S.
648 is controlling and that error of this sort requires automatic
reversal of the penalty judgment. (See People v. Armstrong,

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Opinion of the Court by Kruger, J.

supra, 6 Cal.5th at p. 764.) Riccardi is but one in a long line of
cases, dating back to Witherspoon itself, that have held that
reversal is required.
In applying these rules here, we break no new ground; the
governing law was as clear at the time of trial as it is today.
Indeed, in a case decided several months before jury selection
began in this case, we pointedly reminded trial judges about the
critical importance of carefully adhering to the well-settled
standards and procedures for death-qualifying a jury: “In view
of the extremely serious consequence — an automatic reversal
of any ensuing death penalty judgment — that results from a
trial court’s error in improperly excluding a prospective juror for
cause during the death-qualification stage of jury selection, we
expect a trial court to make a special effort to be apprised of and
to follow the well-established principles and protocols
pertaining to the death qualification of a capital jury. As the
present case demonstrates, an inadequate or incomplete
examination of potential jurors can have disastrous
consequences as to the validity of a judgment. The error that
occurred in this case — introducing a fatal flaw that tainted the
outcome of the penalty phase even before the jury was sworn —
underscores the need for trial courts to proceed with special care
and clarity in conducting voir dire in death penalty trials. The
circumstance that the error in this case was committed by a trial
judge with substantial experience in criminal law renders the
voir dire examination at issue all the more inexplicable and
disappointing.” (People v. Heard, supra, 31 Cal.4th at pp. 966–
967.)
Those remarks apply with full force to this case. Because
the trial court failed to develop a record sufficient to support
excusal of jurors for cause, and because the prosecution did not
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Opinion of the Court by Kruger, J.

speak up as these errors were occurring to ensure an adequate
record, the penalty phase in this case was over before it ever
began. It is in no one’s interest for a capital case to begin with
the certainty that any ensuing death verdict will have to be
reversed and the entire penalty case retried. (See People v.
Heard, supra, 31 Cal.4th at p. 968.) We emphasize what we said
in Heard, and have said many times before and since: Before a
prospective capital juror is dismissed on the basis of death
penalty views, it is imperative that the party seeking dismissal
and the trial court ensure a record adequately establishing those
views is developed. (See, e.g., People v. Buenrostro, supra, 6
Cal.5th at p. 412; People v. Covarrubias (2016) 1 Cal.5th 838,
863–866; People v. Zaragoza (2016) 1 Cal.5th 21, 37–41; People
v. Leon, supra, 61 Cal.4th at p. 592.) Jurors may not be excused
merely for opposition to the death penalty, but only for views
rendering them unable to fairly consider imposing that penalty
in accordance with their oath. The record must make manifest
that inability — not with “ ‘unmistakable clarity’ ” (Witt, supra,
469 U.S. at p. 424), to be sure, but with sufficient clarity that a
reviewing court can identify a basis for the trial court’s
conclusion that the juror actually lacked the requisite ability. In
the absence of such a record, we have no choice but to reverse
the death sentence. (Buenrostro, at pp. 415–418.)
Peterson, however, asks us to go one step further. He
argues that the errors in jury selection affected all parts of his
trial, not just the penalty phase, and rendered the results of the
jury’s guilt phase deliberations unreliable as well. He
accordingly asks that we set aside not only his sentence but the
murder convictions that preceded it. Both the United States
Supreme Court and this court have previously declined to take

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Opinion of the Court by Kruger, J.

this additional step, and Peterson offers no persuasive ground
for doing so here.
The United States Supreme Court in Witherspoon rejected
the argument that errors in death qualifying a jury necessarily
undermine its guilt phase verdict in addition to its penalty
judgment. Invoking surveys and academic studies, Witherspoon
had argued that “the kind of juror who would be unperturbed by
the prospect of sending a man to his death . . . is the kind of juror
who would too readily ignore the presumption of the defendant’s
innocence, accept the prosecution’s version of the facts, and
return a verdict of guilt,” and thus his jury was biased as to guilt
too. (Witherspoon, supra, 391 U.S. at pp. 516–517; see id. at p.
517, fns. 10, 11.) The high court was unpersuaded. While the
court considered it “self-evident” that errors in death
qualification would undermine the jury’s impartiality “in its role
as arbiter of the punishment to be imposed” (id. at p. 518),
Witherspoon’s studies failed to show that the same was true of
the jury in its different capacity as finder of fact (id. at pp. 517–
518; see id. at p. 521, fn. 20 [determination whether to impose
the death penalty “is different in kind from a finding that the
defendant committed a specified criminal offense”]). The court
explained: “We simply cannot conclude, either on the basis of
the record now before us or as a matter of judicial notice, that
the exclusion of jurors opposed to capital punishment results in
an unrepresentative jury on the issue of guilt or substantially
increases the risk of conviction.” (Id. at pp. 517–518.) Despite
a record in which “the prosecution eliminated nearly half the
venire of prospective jurors by challenging . . . any venireman
who expressed qualms about capital punishment” (id. at p. 513),
the high court refused to disturb the guilty verdict (id. at
pp. 518, 522–523, fn. 21). Our own cases have followed the same

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Opinion of the Court by Kruger, J.

path, reversing the death judgment in cases of jury-selection
error but declining to disturb the guilty verdict. (See, e.g.,
People v. Armstrong, supra, 6 Cal.5th at p. 764; People v.
Stewart, supra, 33 Cal.4th at p. 455.)
Peterson candidly acknowledges this precedent, but asks
us to distinguish it on the ground that Witherspoon and
subsequent cases considered only whether the Sixth and
Fourteenth Amendments to the United States Constitution
require a guilty verdict be set aside; Peterson argues the Eighth
Amendment compels a different result. But Peterson’s Eighth
Amendment claim “appears to be merely a restatement of [the]
Sixth Amendment claim[].” (People v. Johnson (1992) 3 Cal.4th
1183, 1213.) Though couched in terms of Eighth Amendment
reliability, as opposed to Sixth Amendment representativeness,
it depends on the identical premise — that the exclusion of
jurors generally opposed to the death penalty tilts the venire to
an unacceptable degree in favor of the prosecution on questions
of guilt as well as sentence. On the record before it, the court in
Witherspoon was unable to say that even systematic exclusion
of those opposed to the death penalty “substantially increase[d]
the risk of conviction.” (Witherspoon, supra, 391 U.S. at p. 518.)
The 1984, 1986, and 1994 studies Peterson cites do not lead to a
different conclusion. He relies on research analyzing how the
constitutionally accepted process of “death qualification” — i.e.,
the dismissal of potential jurors who would either always or
never vote for death — alters the willingness to convict. These
studies do not establish that excluding one — or even 13 —
prospective jurors, from a pool of nearly 1,500, “substantially
increase[s] the risk of error in the factfinding process.” (Beck v.
Alabama (1980) 447 U.S. 625, 632.) Nor does Peterson point to
any evidence in the record to support this claim.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

Peterson argues that even if the errors in jury selection do
not require reversal of his convictions, there were several other
errors that do command that result. We therefore turn to
whether any of these asserted errors in the guilt phase trial
requires that Peterson’s murder convictions be set aside.
B. Denial of Motion to Change Venue
Peterson was arrested and charged in Stanislaus County,
where he and Laci had lived. He moved for a change of venue,
arguing that a fair and impartial trial could not be had in
Stanislaus because of the extensive publicity the case had
received. The Stanislaus County Superior Court granted the
motion and, after considering the alternatives recommended by
the Administrative Office of the Courts,11 including Alameda,
Santa Clara, and Orange Counties, selected San Mateo County
as the best venue. It found that local media coverage and the
degree of community involvement in the case would preclude a
fair trial in Stanislaus, but any county of sufficient size outside
the Central Valley could provide a fair trial. San Mateo was
selected based on its facilities and its relative proximity
compared to Southern California, which would minimize travel
for the many Modesto-area witnesses.
Jury selection began in March 2004. In May 2004,
Peterson filed a second change of venue motion, this time
seeking transfer of the case to Los Angeles County. He argued
that examination of questionnaire answers from prospective
jurors showed, once again, that extensive pretrial publicity was

11
The Administrative Office of the Courts was the name of
a body serving the Judicial Council of California. In 2014, the
name was retired to better reflect that the office was, and is, a
subpart of the Judicial Council.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

affecting the juror pool. The trial court considered the parties’
papers and arguments and made a detailed oral ruling denying
a further venue change. Peterson contends the denial of his
second motion violated his federal constitutional right to trial by
an impartial jury (U.S. Const., 6th & 14 Amends.) and similar
state guarantees.
In a series of cases in the 1960s, the United States
Supreme Court recognized that media publicity about a criminal
trial could in some circumstances deprive the defendant of the
right to trial by an impartial jury. (Sheppard v. Maxwell (1966)
384 U.S. 333; Estes v. Texas (1965) 381 U.S. 532; Rideau v.
Louisiana (1963) 373 U.S. 723; Irvin v. Dowd (1961) 366 U.S.
717; see generally Skilling v. United States (2010) 561 U.S. 358,
378–381.) In the wake of these decisions, to ensure “the
requirement basic to our jurisprudence that every person
accused of crime is entitled to a trial by a fair and impartial jury”
(Maine v. Superior Court (1968) 68 Cal.2d 375, 384), this court
adopted a new standard for pretrial change of venue motions:
Such a motion should “ ‘be granted whenever it is determined
that because of the dissemination of potentially prejudicial
material, there is a reasonable likelihood that in the absence of
such relief, a fair trial cannot be had’ ” (id. at p. 383; see Pen.
Code, § 1033, added by Stats. 1971, ch. 1476, § 3, p. 2915
[codifying the Maine standard]).
Over time, we have elaborated on the prophylactic Maine
standard and identified a series of considerations courts must
weigh to ensure the constitutional right to a fair trial is
preserved. “The factors to be considered are the nature and
gravity of the offense, the nature and extent of the news
coverage, the size of the community, the status of the defendant
in the community, and the popularity and prominence of the
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

victim.” (People v. Harris (1981) 28 Cal.3d 935, 948; accord, e.g.,
People v. Rices (2017) 4 Cal.5th 49, 72.) “On appeal, the defense
bears the burden of showing both error and prejudice. It must
establish a reasonable likelihood both that a fair trial could not
be had at the time of the motion, and that the defendant did not
actually receive a fair trial.” (People v. Smith (2015) 61 Cal.4th
18, 39; see People v. McCurdy (2014) 59 Cal.4th 1063, 1075.)
Alternatively, in rare and “exceptional cases,” a defendant may
show circumstances so “ ‘extraordinary’ ” that a court may
assume no fair trial could be had. (People v. Prince (2007) 40
Cal.4th 1179, 1216.) We accept when supported by substantial
evidence the facts a trial court finds in connection with a motion
to change venue. (Smith, at p. 39; McCurdy, at p. 1075.) As
dictated by Sheppard v. Maxwell, supra, 384 U.S. at page 362
and Maine v. Superior Court, supra, 68 Cal.2d at page 382,
however, we will independently review all the circumstances to
determine whether there was a reasonable likelihood of an
unfair trial. (Smith, at p. 39; McCurdy, at p. 1075.)
Conceding that the other factors were “largely neutral,”
Peterson rests his argument that denial of a second change in
venue was error on a single consideration, the nature and extent
of pretrial publicity. This case was the subject of massive,
worldwide media attention. Peterson asserts, and the People do
not dispute, “that the combination of print media, radio
coverage, television and cable and internet coverage made this
perhaps the most widely covered trial in American history.” The
trial judge remarked, “The only place you could send this case
probably where they wouldn’t [have] hear[d] about it — I’m not
so sure about that — would be send it to Mars, you know. That’s
the only place where you could try this case where nobody would
know anything about it. It’s been all over the world.” We also

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

take as a given that much of this publicity portrayed Peterson
in a negative light. We nonetheless find no error in the trial
court’s denial of Peterson’s second change of venue motion.
Preliminarily, we reject Peterson’s argument that when
unfavorable publicity reaches the saturation level of this case,
any denial of a change of venue motion is presumptively
prejudicial and a defendant need not show an impartial jury
could not be seated. To the contrary, “ ‘it is well-settled that
pretrial publicity itself — “even pervasive, adverse publicity —
does not inevitably lead to an unfair trial.” ’ ” (People v. Prince,
supra, 40 Cal.4th at p. 1216; see Murphy v. Florida (1975) 421
U.S. 794, 799; People v. Harris, supra, 28 Cal.3d at pp. 949–950.)
Rather, a “presumption of prejudice” from excessive publicity
“attends only the extreme case” (Skilling v. United States,
supra, 561 U.S. at p. 381), one in which the “ ‘trial atmosphere
[is] utterly corrupted by press coverage’ ” (id. at p. 380).
Peterson has not shown that the atmosphere outside the
courtroom reached inside the courtroom and categorically
precluded a fair trial.
In similar cases, courts have held that a change of venue
motion may be denied if the change would be futile: “Where
pretrial publicity has been geographically widespread and
pervasive . . . , a court may deny change of venue on the sensible
ground that it would do no good.” (People v. Venegas (1994) 25
Cal.App.4th 1731, 1738.) For cases of a certain profile, it would
be “speculation to suppose the results of jury selection would
have been significantly different in any county. The media
report local trials of notorious crimes in all counties. People read
newspapers and watch television” — and, we may now add, use
the Internet — “in all counties.” (People v. Cooper (1991) 53
Cal.3d 771, 807.) Discussing the trial of members of the Charles
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

Manson family, the Court of Appeal wrote: “It is patently clear
that the crimes charged, as well as the identity and the
involvement of appellants, permeated every corner of this state
with varying degrees of intensity. The ubiquity of media
coverage made any such differential one of insignificant degree.
A change of venue offered no solution to the publicity problem.
Even if venue had been changed, nothing could have prevented
the public media from swinging its attention to that place. The
magnetic pull of such notorious cases is compelling.” (People v.
Manson (1976) 61 Cal.App.3d 102, 176–177; see People v. Davis
(2009) 46 Cal.4th 539, 578–579.)
The same is true here. Precisely because this case was the
subject of such widespread media attention, it is unclear what
purpose a second change of venue would have served. The
publicity the Peterson trial generated, like the trials of O.J.
Simpson, the Manson family, and any number of other so-called
trials of the century before them, was intrinsic to the case, not
the place. This was even more true than in earlier times
because, as Peterson rightly notes, his trial followed the
explosion of cable television and the Internet as sources of
information, facilitating nationwide coverage of the case. For
these reasons, as the trial court aptly observed, “[i]t is
speculation to suppose [the] results of jury selection would be
any different anywhere else.” Media attention followed this case
from Stanislaus County to San Mateo County. Given the level
of public interest, this case would have attracted attention in
any venue in which it was held. There is no rational reason to
think coverage would have been any less in Los Angeles
County — one of the media capitals of the world — if Peterson’s
motion had been granted.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

Against this conclusion, Peterson relies on survey
statistics measuring the levels in Los Angeles County of
awareness and prejudgment of the case, but those statistics do
not support his argument. First, the surveys did not include San
Mateo, so no direct comparisons can be drawn between Los
Angeles and San Mateo. Second, the two other Bay Area
counties surveyed, Alameda and Santa Clara, generally showed
no statistically significant differences from Los Angeles,
although all three counties were statistically significantly
different from Stanislaus, where the case was originally
pending. This led Peterson’s own expert to opine, in support of
moving the case from Stanislaus, that for a fair trial the “best
three counties that are [statistically] fairly close are Los
Angeles, Alameda, and Santa Clara County.” Third, the
statistics derive from a survey taken a full year before the
second change of venue motion and do not show how
prejudgment levels would have changed if the case were
transferred to Los Angeles, and with it the national media
spotlight. (See People v. Davis, supra, 46 Cal.4th at p. 575
[“Because it is impossible to control heightened media attention
in any new venue, it also is virtually impossible to prevent the
knowledge and prejudgment rates for potential jurors living in
a new venue from increasing after the change of venue has
occurred”].)
Instead, in a high-profile case such as this one, provided a
sufficiently large pool is available — and we agree with the trial
court that San Mateo’s 700,000-plus residents provided such a
pool — the better answer is not to change venue yet again but
to rigorously vet potential jurors to screen out those tainted and
irrevocably biased by pretrial publicity, to find 12, plus
alternates, who can decide only on the evidence admitted at

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

trial. Almost inevitably even those qualified for potential
service by a court may have had some prior exposure to the case,
but “[p]rominence does not necessarily produce prejudice, and
juror impartiality, we have reiterated, does not require
ignorance.” (Skilling v. United States, supra, 561 U.S. at p. 381.)
What matters is whether each prospective juror can “ ‘lay aside
his [or her] impression or opinion and render a verdict based on
the evidence presented in court.’ ” (People v. Harris, supra, 28
Cal.3d at p. 950, quoting Irvin v. Dowd, supra, 366 U.S. at
p. 723.)
The trial court here did just this. Indeed, defense counsel
himself acknowledged, “I think the court has exercised
Herculean efforts in trying to get a fair panel here.” Nearly
1,500 prospective jurors were scrutinized. (See People v.
Famalaro (2011) 52 Cal.4th 1, 30 [“The huge number of
prospective jurors initially summoned (1,200) ensured that an
ample number of unbiased prospective jurors remained after the
biased ones had been excused”].) The court observed that “[t]he
66 people we’ve qualified so far have given us [the] assurance”
that they could set aside any prior impressions or opinions and
decide the case only on the evidence, “and the court is satisfied
that that is, in fact, the case.” Ultimately, all 18 jurors and
alternates chosen to serve had indicated in their juror
questionnaires that they had not formed any opinion as to
Peterson’s guilt or innocence because they did not have enough
information to decide. The actual seated jurors thus had no
preliminary opinions on guilt — never mind preset views they
would be unable to set aside.
Peterson argues that the seated jurors’ declarations of
impartiality should be rejected based on his survey data drawn
from the venire as a whole. We agree that “the juror’s
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

assurances that he [or she] is equal to this task cannot be
dispositive of the accused’s rights.” (Murphy v. Florida, supra,
421 U.S. at p. 800.) But Peterson offers no sound basis to believe
the jurors’ assurances in this case were insincere. Almost every
prospective juror had been exposed to publicity about the case,
but this is unsurprising for a case Peterson describes as the most
publicized in American history, and would have been unlikely to
change much in any other county. According to Peterson’s
review of juror questionnaires filled out before the second
motion, 43 percent of prospective jurors (426 of 998) had formed
a preliminary opinion that Peterson was guilty, and 19 percent
(190 of 998), roughly one in five, would not be able to set aside
that view. But this still means that, by the time jury selection
was complete, the parties would have had well in excess of 1,000
avowedly impartial jurors to choose from. “When, as here, there
is a ‘large, diverse pool of potential jurors, the suggestion that
12 impartial individuals could not be empanelled is hard to
sustain.’ ” (People v. Famalaro, supra, 52 Cal.4th at p. 23,
quoting Skilling v. United States, supra, 561 U.S. at p. 382.)
Our confidence in the fairness of the actual jury rests as well on
our independent review of their voir dire, during which the
parties and court carefully vetted them to ferret out bias. (See
Famalaro, at p. 31.) Peterson has not demonstrated the trial
court could not, and did not, find 12 impartial individuals. His
claim that he was denied his right to trial before a fair jury is
without merit.12

12
Irvin v. Dowd, supra, 366 U.S. 717, People v. Tidwell
(1970) 3 Cal.3d 62, and People v. Williams (1989) 48 Cal.3d 1112,
upon which Peterson relies to argue it was error to deny a

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

We acknowledge Peterson’s concern was not just that the
court would be unable to find 12 unbiased jurors. Rather, it was
that they would not stay unbiased; according to defense counsel,
“the problem is that you take that panel that may be fair here,
and you stick them back in the community and you do that on a
daily basis over five months, and you’re not going to be able to
get over the kind of community passion and what I consider to
be a polluted atmosphere.” This challenge, however, is one that
would have had to be addressed in any community to which the
case was relocated, and one the trial court took appropriate
efforts to address. A second change of venue was not the answer,
and the trial court did not err in saying so.
C. Admission of Dog Scent Trailing Evidence
Before trial, the court held an Evidence Code section 402
hearing to determine whether to admit the prosecution’s
evidence of dogs trailing Laci’s scent from her home in Modesto,
in and around Peterson’s warehouse in Modesto, on highways
leaving Modesto, and at the Berkeley Marina. After extensive
testimony from and cross-examination of various dog handlers
concerning their training, as well as their dogs’ training and
past performance, the court excluded all dog scent trailing
evidence as lacking in sufficient foundation and corroboration,

change of venue, are not comparable. In Irvin, in marked
contrast to this case, eight of the 12 actual jurors thought the
defendant guilty before trial even began. (Irvin, at p. 727.) And
in both Tidwell and Williams, the small size of the venues
(Lassen and Placer Counties, respectively) and the comparative
prominence of the victims and defendants within those
communities — factors notably absent here — weighed in favor
of concluding that a change of venue would have made a
difference. (Tidwell, at pp. 72–73; Williams, at pp. 1126–1129.)

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

except for evidence of scent trailing at the Berkeley Marina. The
court explained that all the dog-trailing evidence in and around
Modesto lacked sufficient independent corroboration that Laci
had ever been where dogs purported to trail her scent. The
Berkeley Marina evidence differed because there was
corroborating evidence that Laci had been present in the area —
namely, that Laci’s remains washed ashore on the edge of the
San Francisco Bay, very near the marina.
Consistent with the trial court’s ruling, dog handler Eloise
Anderson, a member of the Contra Costa County Sheriff’s
Department search and rescue team, testified at trial about
scent trailing she conducted at the Berkeley Marina with her
dog Trimble. Anderson reported to the marina with Trimble on
December 28, 2002, four days after Laci’s disappearance.
Anderson was provided a glasses case containing a pair of Laci’s
sunglasses and asked to work with her dog to determine
whether any trail of Laci’s scent could be detected. The marina
harbor had two separate access points where someone might
enter, so Anderson had Trimble check each entry point.
Wearing rubber gloves to conceal her own scent, Anderson
opened the glasses case to expose the sunglasses inside,
presented the case with the sunglasses to Trimble, and gave a
trailing command. In the first location, Trimble responded with
a “no scent trail” signal. In the second location, Trimble “lined
out,” pulling her harness line taut, with level head, and taking
Anderson from an area near the parking lot down one of the
marina piers to a pylon on the pier where a boat could have been
tied, then giving Anderson an “end of trail” signal.
Peterson argues admission of this evidence of dog trailing
at the Berkeley Marina was error because the trial court failed
to require a hearing under People v. Kelly (1976) 17 Cal.3d 24
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

(Kelly), and the prosecution failed to establish the legally
required foundation. We disagree.
When admission of expert testimony relating the use of
novel scientific methods or techniques is at issue, the proponent
of the evidence must demonstrate the technique’s reliability
through testimony from an expert qualified to opine on the
subject. The technique’s reliability, in turn, depends on a
showing that it has achieved general acceptance among
practitioners in the relevant field. Finally, the proponent of the
evidence must show any procedures necessary to ensure the
technique’s validity were properly followed in the given case.
(Kelly, supra, 17 Cal.3d at p. 30.) The purpose of these threshold
requirements — commonly referred to as the Kelly test — is to
protect against the risk of credulous juries attributing to
evidence cloaked in scientific terminology an aura of
infallibility. (Id. at pp. 31–32.)
Not every subject of expert testimony needs to satisfy the
Kelly test. Courts determining whether Kelly applies must
consider, first, whether the technique at issue is novel, because
Kelly “ ‘only applies to that limited class of expert testimony
which is based, in whole or part, on a technique, process, or
theory which is new to science and, even more so, the law.’ ”
(People v. Jackson (2016) 1 Cal.5th 269, 316 (Jackson).) Second,
courts should consider whether the technique is one whose
reliability would be difficult for laypersons to evaluate. A “Kelly
hearing may be warranted when ‘the unproven technique or
procedure appears in both name and description to provide some
definitive truth which the expert need only accurately recognize
and relay to the jury.’ ” (Jackson, at p. 316.) Conversely, no
Kelly hearing is needed when “[j]urors are capable of
understanding and evaluating” the reliability of expert
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

testimony based in whole or in part on the novel technique.
(Jackson, at p. 317.)
Several decades ago, in People v. Craig (1978) 86
Cal.App.3d 905 (Craig), addressing an issue then of first
impression in California, the Court of Appeal concluded no Kelly
hearing was needed before introducing dog-trailing evidence.
The court explained that dog trailing does not involve
standardized techniques and inanimate, fungible instruments
whose accepted use in the scientific community may be
established, but individual dogs, whose “ability and reliability
[should] be shown on a case-by-case basis.” (Craig, at p. 915.)
As such, Kelly does not apply; the evidence is admissible if
proper foundation is laid concerning the present ability of a
particular well-trained dog to trail a human. This “is a fact
which, like other facts, may be proven by expert testimony.”
(Ibid.)
The Court of Appeal in People v. Malgren (1983) 139
Cal.App.3d 234 (Malgren) elaborated on the foundation
necessary to introduce dog-trailing evidence. Drawing from the
analyses of sister state courts that had wrestled with the same
problem, the court identified five points a proponent must
establish: “(1) the dog’s handler was qualified by training and
experience to use the dog; (2) the dog was adequately trained in
tracking humans; (3) the dog has been found to be reliable in
tracking humans; (4) the dog was placed on the track where
circumstances indicated the guilty party to have been; and
(5) the trail had not become stale or contaminated.” (Id. at
p. 238, disapproved in part by Jackson, supra, 1 Cal.5th at
p. 325 [last factor duplicative; see discussion, post].)

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

When this court first addressed these issues in Jackson,
supra, 1 Cal.5th 269, we endorsed the general approach of Craig
and Malgren. We agreed that unlike the sorts of scientific
evidence a juror might uncritically accept, for which a threshold
Kelly hearing should be held, “[s]cent trailing evidence is not so
foreign to everyday experience that it would be unusually
difficult for jurors to evaluate. Jurors are capable of
understanding and evaluating testimony about a particular
dog’s sensory perceptions, its training, its reliability, the
experience and technique of its handler, and its performance in
scent trailing” in a given case. (Jackson, at p. 317.) We thus
approved the general admissibility of “[e]vidence grounded in
the ability of particular dogs to perform scent trailing on
command . . . so long as a proper foundation is laid.” (Id. at
p. 320.)
In discussing the necessary foundation, we adopted the
Malgren factors with one modification. A proponent must
establish as background qualifications the adequacy of the
handler’s and dog’s training and supply evidence of the dog’s
reliability in trailing humans. (Jackson, supra, 1 Cal.5th at
pp. 321–322.) The party must also show the adequacy of the
manner in which the dog was given a scent to trail, whether (as
in Craig and Malgren) by being allowed to sniff the beginning of
a known trail or (as in Jackson) by being “presented with a scent
article” and then asked to smell for a corresponding trail of the
same scent. (Jackson, at p. 322.) We also approved the
corroboration requirement established in Craig, Malgren, and
People v. Gonzales (1990) 218 Cal.App.3d 403, 409 (Gonzales) —
the need for some independent evidence tending to confirm that
a person found at the end of the trail the dog followed was indeed
the person who left the scent trail and supplied the initial scent.

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

(Jackson, at p. 321.) We concluded the remaining Malgren
condition for admissibility — evidence the source of the initial
scent had not become stale or contaminated — was essentially
duplicative of the other elements and thus need not be shown
independently. “If a well-qualified handler trains a dog who has
reliably trailed human scent and is well trained in ignoring or
forgetting past smells and in indicating negative trails, then the
dog will not trail if the scent on the scent item is stale or
nonexistent, or if there is no trail that matches the scent on the
scent item.” (Jackson, at p. 325.) Thus, evidence of the
remaining Malgren requirements ordinarily will suffice to
support admission of dog-trailing evidence. (See People v.
Westerfield (2019) 6 Cal.5th 632, 706.)
As in Jackson, we conclude the trial court did not err in
declining to subject the dog-trailing evidence to the threshold
Kelly test. The nature of the dog-trailing technique at issue here
is not meaningfully different from the technique at issue in
Jackson, which we concluded was not subject to Kelly. In
Jackson, on one occasion, a trained dog was given a gauze pad
infused with scent from a fresh shoe print left outside a victim’s
house and then taken to a lobby through which a suspect had
passed. The dog was able to trail from the lobby to an interview
room where the suspect was sitting, whereupon the dog alerted
to the suspect. (Jackson, supra, 1 Cal.5th at pp. 308–309.) On
a second occasion, a dog was given a gauze pad infused with
scent from an envelope left on a different victim’s bed and
believed to have been handled by the perpetrator. The dog was
again asked to seek out and follow any matching trail, and
trailed from a point outside the police station to a locker room
inside the station, where the suspect was sitting, and again
alerted to the suspect. (Id. at p. 309.) The essential task the dog

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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

was asked to perform was to “follow any human scent that she
could pick up from the envelope.” (Id. at p. 320.) Here, Trimble’s
task was not fundamentally different in nature: She was
presented with Laci’s sunglasses and then directed to smell for
trails of the same human scent, if any, at the Berkeley Marina.
This was not a novel technique; indeed, Anderson testified that
teaching a dog to scent off an object and then seek a
corresponding trail is a routine part of training dogs to trail
humans. Nor was it a technique whose fallibility would have
been opaque to laypersons. Under Jackson, no Kelly hearing
was necessary before the evidence was admitted, provided that
the requisite foundational requirements were satisfied.
Turning to that necessary foundation, Peterson argues we
should supplement the requirements set out in Jackson with
additional requirements derived from the Court of Appeal’s
decisions in People v. Willis (2004) 115 Cal.App.4th 379 (Willis)
and People v. Mitchell (2003) 110 Cal.App.4th 772, 790–794
(Mitchell). We declined to impose these requirements in
Jackson, and there is no reason for a different result here.
(Jackson, supra, 1 Cal.5th at pp. 319–320.)
In Willis, the dog was not asked to smell for a scent trail,
but instead was exposed to a scent and then “watched to see if
the dog ‘show[ed] interest’ in various locales frequented by the
defendant.” (Willis, supra, 115 Cal.App.4th at p. 386.) This sort
of scent identification, the court held, should be admissible only
upon foundation concerning such matters as “how long scent
remains on an object or at a location” and “whether every person
has a scent that is so unique that it provides an accurate basis
for scent identification.” (Ibid., citing Mitchell, supra, 110
Cal.App.4th at pp. 791–792.) In Mitchell, on which Willis relied,
a dog had been given pads with scent from murder shell casings
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

and the victim’s shirt and a lineup of pads with scents from
various people, including the defendants. The dog alerted to a
match with pads containing one defendant’s scent, but not the
other’s. (Mitchell, at pp. 780–781.) The Court of Appeal
distinguished between scent trailing, which was established as
admissible without any Kelly hearing, and a scent lineup of the
sort performed in Mitchell. (Mitchell, at p. 790.) Such a lineup,
the court reasoned, did not have the kind of centuries-long
lineage that scent trailing does, and thus ought to be supported
by additional foundation establishing the uniqueness of human
scents and their persistence and rate of degradation. (Id. at
pp. 793–794.)
Here, the dog-trailing evidence admitted at trial did not
resemble either the open-ended identification at issue in Willis
or the scent lineup at issue in Mitchell. Trimble was not asked
to match a scent to a general location the target may have
frequented at unspecified times in the past, nor was she asked
to distinguish among multiple people or objects on the basis of
their scents. Rather, Trimble was asked to seek out and follow
a trail, if any could be found, based on a given scent. Jackson
rejected the need for additional foundation tied to scent
identification before introducing evidence of a dog’s performance
of a very similar task. (Jackson, supra, 1 Cal.5th at pp. 319–
320.) No more foundation than that required by Malgren and
Jackson for analogous tasks was necessary here.
Again, under the Malgren test, as modified in Jackson, the
prosecution was required to show that Anderson was sufficiently
trained, that Trimble was sufficiently trained and reliable in
tracking humans, that Trimble was properly given an initial
scent to trail, and that some evidence tended to corroborate
Trimble’s trailing. We review the trial court’s determination
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that adequate foundation was laid for abuse of discretion.
(Jackson, supra, 1 Cal.5th at p. 321.) If substantial evidence
supports each foundational element, the decision to admit dog-
trailing evidence will be upheld. (Ibid.; Craig, supra, 86
Cal.App.3d at p. 917.)
Anderson testified about her experience over more than
two decades training dogs. She described her dog Trimble’s
certificates and training, which included certification in trailing
from the California Rescue Dog Association and repeated
seminars and training exercises over a period of years leading
up to her use in trailing Laci’s scent in December 2002.
Trimble’s training included out-of-state sessions to give her
experience trailing under varied environmental factors, terrain,
and weather conditions. Anderson described many of Trimble’s
successful human scent trailings, including numerous instances
of trailing noncontact trails13 and successfully following trails
four days old or even older.14 Anderson opined that Trimble was
reliable in trailing humans. Based on the foregoing evidence,
which was substantial, the trial court made specific findings

13
A noncontact trail is one left by a person not in contact
with the ground, as on a bicycle or in a vehicle.
14
For example, in a November 1999 exercise, Trimble
successfully trailed a person who had left a trail largely on
asphalt, which retains scent more poorly than vegetation. The
trail was five days old and there had been intervening
rainstorms. In a December 2001 exercise, Trimble successfully
followed a four-day-old noncontact trail left by a bicyclist riding
the 30 miles from Walnut Creek to Dublin. Given the length of
the trail, it was not physically possible for Trimble to cover the
entire distance, so at various points she was driven from one
section of the trail to a later section, but she was able to relocate
and follow the bicyclist’s scent each time.

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that Anderson and Trimble were adequately trained and
Trimble was reliable at tracking humans.
The fourth Malgren element, the adequacy of the fashion
in which the dog was given a scent to trail, was established with
testimony that Trimble was exposed to a scent object of Laci’s,
her sunglasses. (See Jackson, supra, 1 Cal.5th at p. 322.) This
case is thus unlike Willis, where the dog was given an initial
scent from a matchbook but the prosecution failed to present any
“proof that [the target] ever touched the matchbook from which
a scent was collected.” (Willis, supra, 115 Cal.App.4th at p. 386.)
Finally, the court found corroboration of Trimble’s trailing —
reason to think her identification of Laci’s scent along a path
down to the water was accurate — from evidence that Laci’s
body would, some months later, wash ashore not far from the
marina. That evidence, and its tendency to give credence to
Trimble’s trailing, are beyond reasonable dispute.15 Substantial
evidence supports the court’s determination that the Berkeley
Marina dog-trailing evidence was admissible.

15
In his reply brief, Peterson challenges the trial court’s
ruling on the ground that the prosecution presented no other
evidence proving Laci was at the Berkeley Marina. This is true,
but it was not an unreasonable inference based on the evidence
that was presented. Laci disappeared in Modesto, California, a
90-mile drive inland from Berkeley; her remains washed ashore
in the San Francisco Bay, just two to two and one-half miles
from the marina; and the marina was one of the closest access
points to the bay from Modesto. These facts offer some reason
to believe Laci, or her body, was taken to the San Francisco Bay
by way of the marina. This is to say nothing of the other
evidence that Peterson was responsible for Laci’s disappearance
and, by his own admission, was at the Berkeley Marina on
December 24. The trial court did not err in holding that the
corroboration element had been satisfied.

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Peterson does not contest the sufficiency of this testimony
to establish that Anderson and Trimble had sufficient training
in trailing scents and that Trimble had shown herself generally
capable of identifying and following human scents. He argues,
however, that the prosecution failed to establish specific
essential qualifications for both Anderson and Trimble: that
Anderson had specialized training to avoid certain handler
behaviors, and that Trimble had demonstrated success in
particular conditions mirroring those at the Berkeley Marina.
Regarding Anderson’s training, Peterson argues that
Anderson never testified her training included specific
instruction on how to avoid cueing dogs to go in a desired,
predetermined direction when trailing. Neither we nor the
Courts of Appeal have ever held such specific testimony a
mandatory prerequisite. (Cf. Florida v. Harris (2013) 568 U.S.
237, 244 [in the context of warrantless searches challenged
under the 4th Amend., the reliability of a drug-sniffing dog
should be evaluated under the totality of the circumstances,
rather than according to a “strict evidentiary checklist”].)16 Nor
did Peterson argue to the trial court that this more specific

16
Peterson argues that other jurisdictions require testimony
concerning cue avoidance, but review of the published case law
he relies on and subsequent decisions belies the assertion.
Although some of the cases he cites have referred to such
testimony, or the absence thereof, in passing, none holds that
such testimony is necessary before dog-trailing evidence may be
admitted. (See U.S. v. Trayer (D.C. Cir. 1990) 898 F.2d 805, 809;
U.S. v. One Million, Thirty-Two Thousand, Nine Hundred
Eighty Dollars in U.S. Currency ($1,032,980.00) (N.D.Ohio
2012) 855 F.Supp.2d 678, 699; Harris v. State (Fla. 2011) 71
So.3d 756, 768–769, revd. sub nom. Florida v. Harris, supra, 568
U.S. 237; State v. Helzer (2011) 350 Or. 153, 158–159 [252 P.3d
288]; State v. England (Tenn. 2000) 19 S.W.3d 762, 768–769.)

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foundation should have been supplied, at a time when the
prosecution would have had the opportunity to rectify any
perceived omission. It is therefore too late to raise the issue
now. (See Florida v. Harris, at pp. 248–249 [failure to voice in
the trial court doubts about the sufficiency of dog’s training bars
raising those concerns for the first time on appeal].)
In any event, the record does demonstrate that Anderson
was aware of the dangers of trainer cueing and sought to avoid
them. She testified that she did everything possible to remain
neutral and trained Trimble in specific ways to ignore her as
much as possible, and that their joint training included
successfully working numerous blind trails where neither knew
in advance where the subject had gone. During cross-
examination of prosecution witnesses, in the defense case, and
in closing argument, Peterson was free to address whether
Trimble’s performance at the marina was tainted by trainer
cueing. (See Florida v. Harris, supra, 568 U.S. at pp. 246–247
[proof of certification or successful completion of a training
program supports presumption of dog’s reliability, but subject to
cross-examination and introduction of conflicting evidence by
the defendant]; Jackson, supra, 1 Cal.5th at p. 297 [defendant
introduced expert testimony that particular dog-trailing
evidence was unreliable because the procedure used permitted
inadvertent cueing].) He chose not to. Of course, had Peterson
done so, the prosecution could have argued that if Trimble was
merely responding to her handler’s subconscious desire to find a
path, she would have done so in the first place they checked,
rather than giving her handler a “no trail” signal. Ultimately,
whether cueing might have affected Trimble’s performance is a
matter the jury could consider in deciding what weight to give
it, but the absence of testimony about specific training designed

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to avoid cueing did not render the evidence categorically
inadmissible.
Peterson next argues that the prosecution was required to
present foundation that Trimble was reliable in the specific
conditions under which she performed scent trailing at the
marina. We have never required, and see no basis for
demanding, that the proponent of dog-trailing evidence
demonstrate past performance in conditions that are identical
to the case at hand. All the training and experience a dog
receives has relevance in assessing the dog’s reliability in
trailing humans. (Jackson, supra, 1 Cal.5th at p. 322 [trial court
finding of reliability supported by generalized training]; see
Florida v. Harris, supra, 568 U.S. at pp. 244–247 [totality of the
circumstances relevant to assessing drug-sniffing dog’s
reliability].) As with the cueing issue just addressed, a
defendant is free to introduce evidence, cross-examine
witnesses, and present argument that aspects of the trailing
environment made the detection of a scent trail more fraught
and subject to error. But the failure of a particular dog to have
trailed in circumstances precisely mirroring those in a given
case does not preclude the jury from considering trailing
evidence.
Nor, in any event, do the specific features of the marina
trailing undermine the soundness of the trial court’s
determination that the prosecution’s foundation was adequate.
Peterson emphasizes that the trailing involved a “marine”
environment. Trimble was not asked to trail at sea; she was
asked to trail in a field, parking lot, and dock that were adjacent
to a body of water. Peterson offered no evidence that trailing on
land in an area adjacent to a body of water poses significant

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difficulties.17 Peterson also stresses the noncontact nature of
the trail, but Anderson testified at length about Trimble’s many
successful trailing exercises involving noncontact trails.
Lastly, under the prosecution’s theory, Laci’s body was
covered by a tarp when she was in the marina, and so Peterson
highlights the fact that Trimble’s one undisputed failure in a
training exercise had involved an enclosed target. But the
prosecution presented evidence that on a different occasion,
Trimble had previously successfully trailed an enclosed target,
following a trail generated by a subject in the closed trunk of a
car.18
Of course, Peterson was also entitled to try to undercut
Anderson’s testimony by pointing to Trimble’s track record in
trailing enclosed targets, and he did just that: He cross-
examined Anderson about Trimble’s failure, as well as the more
general difficulties with following a trail left by someone in a
closed vehicle. The jury was then specifically instructed that in
weighing testimony concerning Trimble’s performance, it could
consider “any other factor that could affect the accuracy of the
dog tracking evidence.” The particular circumstances involved
in the trailing exercise here may have made Trimble’s task more
or less difficult, but they did not alter the fundamental nature
of the task — which, again, is the type of task dogs have
performed for centuries. Those circumstances were thus

17
Indeed, Christopher Boyer, the head of the Contra Costa
County Sheriff’s Department’s search and rescue team, testified
that humidity enhances the ability of scent to adhere to surfaces
and may make it easier for dogs to trail.
18
A third test Peterson cites, from October 2002, was the
subject of vigorous debate as to whether Trimble succeeded and
whether the test was even an enclosed-target test.

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relevant to the weight the jury might accord this evidence, but
not its admissibility.
Finally, Peterson argues that the dog-trailing evidence
should have been excluded because Anderson failed to perform
a “missing member” test on Laci’s sunglasses. Anderson
explained that when a scenting object has two “equally intense”
scents on it, a handler may present the object and then have the
dog smell the target she does not want the dog to trail. Trailing
dogs are then taught to seek out a trail that matches the
remaining scent — the person that is missing, i.e., the “missing
member.” Peterson suggests it is possible that he may have
touched Laci’s sunglasses at some point in the past. He argues
Anderson therefore should have performed a missing member
check to eliminate the possibility that Trimble was following
Peterson’s own scent from when he was, concededly, at the
Berkeley Marina a few days earlier.
There are two difficulties with this argument. First,
Anderson testified, and Peterson does not dispute, that trailing
dogs are trained to follow the freshest, most recent scent on a
particular object. There is no evidence in the record that
Peterson handled Laci’s sunglasses so recently that his scent
would be equally fresh and risk confusing Trimble. Indeed,
there is nothing in the record to show Peterson handled the
sunglasses at all. The most Peterson can point to is hearsay,
inadmissible for its truth, that Peterson had handled Laci’s
purse at some unspecified time in the past. Second, and in any
event, conducting a missing member test is not a foundational
requirement for admission of dog-trailing evidence. Peterson
does not dispute that Laci handled her own sunglasses, and that
Trimble was then given the sunglasses as a scent object before
attempting to find a trail. Given this, the prosecution
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adequately established foundation for the fourth Malgren
factor — “that the dog was presented with a scent article that
the jury could infer was handled by” the target. (Jackson, supra,
1 Cal.5th at p. 322.) Whether Peterson also handled the
sunglasses so recently Trimble became confused was a matter
he could, and did, argue to the jury. (See id. at pp. 325–326
[even when foundation established, defendant free to cross-
examine witnesses and present rebuttal evidence].) But
Peterson fails to establish that the evidence rested on an
inadequate foundation to support its admission.
For the same reasons, Peterson fails to establish that
admission of the evidence violated his federal constitutional
right to a reliable guilt determination in a capital case. (U.S.
Const., 8th & 14th Amends.) The dog-trailing evidence was not,
as defendant claims, inherently unreliable; it rested on a solid
foundation and could fairly be considered by the jury alongside
whatever arguments against its significance and accuracy
Peterson chose to muster.
While we see no error in the admission of Trimble’s scent
trailing, we also see no reasonable possibility that the jury
would have returned a different verdict had the scent trailing
evidence been excluded. Peterson contends that the evidence
was crucial because the prosecution relied heavily on it. But the
prosecutor devoted only a few sentences to the subject in the
course of closing and rebuttal arguments that stretched for 150
pages of transcript. If credited by the jury, the trailing evidence
would have shown Laci was at the Berkeley Marina in late
December 2002. The jury, however, already knew Laci’s body
had been deposited in the San Francisco Bay months before she
washed ashore in April 2003, and there were a limited number
of access points, among which the Berkeley Marina was closest
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

to where she was found. The trailing evidence did not add much
beyond what could already be inferred from other evidence. It
also did not rule out the defense’s theory “that somebody [else]
abducted her” and then disposed of her in the bay. And the
trailing testimony aside, there was considerable other
circumstantial evidence incriminating Peterson, from the
simple fact that Laci’s and Conner’s bodies washed ashore 90
miles from their home but within sight of where Peterson
admitted he went fishing the day they disappeared; to the
research Peterson did on bay currents in the weeks preceding
her disappearance and the fishing boat he bought but mentioned
to no one; to Peterson’s inability to explain what he was fishing
for in the middle of the day; to his repeated subsequent
surreptitious trips to the marina in the weeks after her
disappearance; to the many steps he took in the weeks after she
went missing — selling her car, exploring sale of the house,
turning the nursery into a storage room — that indicated he
already knew Laci and Conner were never coming back. Even
under the most stringent harmlessness standard, for federal
constitutional error (Chapman v. California (1967) 386 U.S. 18,
24), it is clear beyond a reasonable doubt exclusion of the limited
dog-trailing evidence admitted by the trial court would have had
no impact on the jury’s determination that Peterson was guilty.
D. Instructions on Dog Scent Trailing Evidence
1. CALJIC No. 2.16 Does Not Provide an Alternate
Theory of First Degree Murder
The jury was instructed with a modified version of
CALJIC No. 2.16, which provided guidance concerning how to
evaluate the dog-trailing evidence that had been introduced.
Peterson argues that the instruction permitted the jury to find
him guilty of first degree murder, without proof of malice, based
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PEOPLE v. PETERSON
Opinion of the Court by Kruger, J.

solely on the dog-trailing evidence once its accuracy was
corroborated. This is incorrect.
Because the dog-trailing evidence involved following the
scent of a missing victim, not a suspect, the court slightly
modified CALJIC No. 2.16. The jury was instructed: “Evidence
of dog tracking of the victim has been received for your
consideration. This evidence is not, by itself, sufficient to permit
an inference that the defendant is guilty of the crime of murder.
Before guilt may be inferred, there must be other evidence that
supports the accuracy of the dog tracking evidence. The
evidence can be direct or circumstantial, and must support the
accuracy of the dog tracking evidence. [¶] In determining the
weight to give to dog tracking evidence, you should consider: [¶]
One, whether or not the handler was qualified by training and
experience to use the dog; [¶] Two, whether or not the dog was
adequately trained in tracking humans; [¶] Three, whether or
not the dog has been found reliable in tracking humans; [¶]
Four, whether the dog was placed on the track where
circumstances have shown the victim to have been; [¶] Five,
whether or not the trail has become stale or contaminated by
the environment, weather, or any other factor; [¶] And, six, any
other factor that could affect the accuracy of the dog tracking
evidence.”
Peterson focuses specifically on one sentence in the
instruction: “Before guilt may be inferred, there must be other
evidence that supports the accuracy of the dog tracking
evidence.” As we have previously noted (see Jackson, supra, 1
Cal.5th at p. 336), this portion of the instruction restates the law
as set forth in a 1990 Court of Appeal decision, Gonzales, supra,
218 Cal.App.3d 403. Like other California courts that had
previously addressed the issue (see Malgren, supra, 139
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Opinion of the Court by Kruger, J.

Cal.App.3d at pp. 241–242; Craig, supra, 86 Cal.App.3d at
p. 918), Gonzales held that dog-trailing evidence requires
corroboration, and it explained why. Corroboration is necessary
not because a dog might be untrustworthy — the reason
corroboration is required in the case of accomplice testimony —
but because it might be inaccurate. (Gonzales, at pp. 410–412.)
Without the ability to question a dog, we cannot be as sure that
on a given occasion the dog correctly identified a starting scent
and thereafter correctly located and followed a trail of that scent
to a given destination. (Id. at pp. 412–413.) Uncertainty as to
the underlying accuracy of the trailing undermines the
reliability of any inferences one might otherwise draw from the
trailing evidence. (See id. at p. 412.) The corroboration
requirement mitigates that uncertainty, ensuring there are
“other circumstances supporting the accuracy of the inferences
drawn from the dog-tracking evidence.” (Id. at pp. 413–414; see
id. at p. 414 [“corroborating evidence . . . allows assurance that
the inferences we draw from any of the various pieces of
circumstantial evidence, including the dog-tracking evidence,
are correct”].)
As relevant here, however, Gonzales made clear that
corroboration does not automatically permit a jury to leap from
acceptance of the dog’s accuracy to the ultimate conclusion of
guilt. The inferences each bit of circumstantial evidence may
support are but an intermediate step in the process. (See
Gonzales, supra, 218 Cal.App.3d at p. 414 [“As with any
circumstantial reasoning process, the ultimate conclusion is
predicated upon many inferences that are drawn” from various
pieces of circumstantial evidence, including dog trailing
evidence].) Without corroboration, the accuracy of dog trail
evidence is too uncertain to support any inferences; with

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corroboration, that evidence may support one or more
inferences, which in turn may be relied upon by a jury to reason
its way to a final conclusion concerning guilt.
Although Peterson contends otherwise, CALJIC No. 2.16
does correctly capture these principles. (See Jackson, supra, 1
Cal.5th at p. 336.) According to the portion in dispute here, dog
trailing “evidence is not, by itself, sufficient to permit an
inference that the defendant is guilty of the crime of murder.
Before guilt may be inferred, there must be other evidence that
supports the accuracy of the dog tracking evidence. The
evidence can be direct or circumstantial, and must support the
accuracy of the dog tracking evidence.” In other words,
independent corroborating evidence of the dog’s accuracy on the
occasion in question is required foundation before any inference
pointing toward guilt may be drawn. The instruction is not
reasonably read, as Peterson suggests, to equate an inference of
guilt based on a single piece of evidence with the ultimate
conclusion that the defendant is guilty beyond a reasonable
doubt. (See Gonzales, supra, 218 Cal.App.3d at p. 414.)
We see no reasonable likelihood the jury was confused on
this point. Here, the trial court concluded the Berkeley Marina
dog-trailing evidence could go to the jury because there was
corroboration that Trimble had accurately extracted Laci’s scent
from her sunglasses and then trailed that scent to the end of a
pier in the marina — specifically, the fact Laci’s body was later
found on the shores of the San Francisco Bay, at a point a
relatively short distance from the marina. If the jury credited
Trimble as accurate, it could then draw inferences pointing
toward Peterson’s guilt — such as that, within days of the
December 28, 2002, trailing, Laci (whether then alive or dead)
was at a pier in the marina where Peterson admitted he had
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been. But as the remainder of the jury instructions made clear,
the ultimate conclusion that Peterson had committed
premeditated murder would require far more. Moments after
instructing the jury with CALJIC No. 2.16, the court gave the
jury complete, detailed instructions reminding it that a guilty
verdict required every element of a charged crime be proved
beyond a reasonable doubt, and spelling out each element that
must be shown to prove first degree murder. Reasonably
understood, CALJIC No. 2.16 did not supplant these
instructions or suggest the jury could bypass considering
whether each and every element had been proven beyond a
reasonable doubt based solely on the dog-trailing evidence.
2. CALJIC No. 2.16 Did Not Violate Any Right to
Balanced Instructions
Peterson argues that the court’s dog-trailing evidence
instruction was flawed in a second way: It referred to the
inculpatory value of dog-trailing evidence without also alluding
to its potential exculpatory value. In support of the argument,
he emphasizes that the prosecution’s evidence was not the only
dog-trailing evidence introduced at trial. Peterson presented
evidence that on December 28, 2002, the same day Trimble
trailed Laci’s scent at the Berkeley Marina, a different dog, T.J.,
was unable to trail Laci’s scent at the marina. Peterson
contends the trial court’s dog-trailing instruction was unfairly
one-sided in that it told the jury about the circumstances under
which the dog-trailing evidence could be used to convict, without
also mentioning that the evidence could be used to support
acquittal. We are unpersuaded.
Peterson’s argument rests on an analogy to Cool v. United
States (1972) 409 U.S. 100 (Cool). There, an alleged accomplice
of the defendant gave exculpatory testimony. (Id. at p. 103,
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fn. 4.) Despite the exculpatory character of the evidence, the
court instructed the jury that it could rely on the evidence to
convict, never mentioning that the jury could also rely on the
evidence to acquit: “ ‘I further instruct you that testimony of an
accomplice may alone and uncorroborated support your verdict
of guilty of the charges in the Indictment if believed by you to
prove beyond a reasonable doubt the essential elements of the
charges in the Indictment against the defendants.’ ” (Ibid.) The
Supreme Court concluded this instruction required reversal:
“[E]ven if it is assumed that [the alleged accomplice’s] testimony
was to some extent inculpatory, the instruction was still
fundamentally unfair in that it told the jury that it could convict
solely on the basis of accomplice testimony without telling it that
it could acquit on this basis.” (Ibid.) Peterson contends that
here, as in Cool, due process required an instruction that
explicitly informed the jury it could acquit on the basis of dog-
trailing evidence.
The analogy to Cool fails for several reasons. First, as just
discussed, the instruction did not tell the jury it could convict
based on the dog-trailing evidence alone. Rather, it told the jury
that such evidence, if (and only if) corroborated, could be used to
support an inference of guilt. An inference is not the same as a
conclusion that each element has been shown beyond a
reasonable doubt (see ante, at pp. 60–62), and so the instruction
here did not replicate the defect in Cool: It did not put a thumb
on the scale of the jury’s deliberations by informing them they
could return a guilty verdict based entirely on one piece of the
prosecution’s evidence. It instead placed limits on the
circumstances in which the jury could consider the prosecution’s
dog-trailing evidence, along with other evidence, as supporting
a conclusion of guilt.

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Source: Frix Law Library, https://www.frixlaw.com/law-library/cases/4558196. Public record. Not legal advice.