Title: People v. Peterson
Citation: N/A
Docket Number: S132449
State: California
Issuer: California Supreme Court
Date: August 24, 2020

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. 
 
2 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
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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.  
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
4 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
5 
 
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. 
 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
6 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
7 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
8 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
9 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
10 
 
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, 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
11 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
12 
 
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. 
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Opinion of the Court by Kruger, J. 
 
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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.  
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
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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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
15 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
16 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
17 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
18 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
19 
 
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, 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
20 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
21 
 
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.) 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
22 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
23 
 
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 
 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
24 
 
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.) 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
25 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
26 
 
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.  
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
27 
 
[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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
28 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
29 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
30 
 
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, 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
31 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
32 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
33 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
34 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
35 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
36 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
37 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
38 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
39 
 
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.   
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
40 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
41 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
42 
 
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 
 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
43 
 
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.) 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
44 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
45 
 
(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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
46 
 
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].) 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
47 
 
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.  
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
48 
 
(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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
49 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
50 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
51 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
52 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
53 
 
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.) 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
54 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
55 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
56 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
57 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
58 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
59 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
60 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
61 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
62 
 
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 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
63 
 
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, 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
64 
 
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. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
65 
 
Second, it would have made no sense to impose similar 
limits on the defense’s dog-trailing evidence; the dog the defense 
pointed to did not find any trail, so there was no trailing 
evidence that would require corroboration.  And, of course, no 
limiting instruction was necessary to allow the defense to use its 
dog-trailing evidence for the purpose it desired:  that is, as 
reason for the jury not to give the prosecution’s dog-trailing 
evidence much weight.  The defense could, and did, argue that 
T.J.’s failure to find a trail on December 28 pointed to Trimble 
having been mistaken. 
Finally, and in any event, the dog-trailing evidence here 
was of substantially less moment in the context of the overall 
case than the accomplice testimony in Cool.  There, the 
defendant “relied primarily on the testimony of” the alleged 
accomplice.  (Cool, supra, 409 U.S. at p. 101.)  The 
“Government’s position clearly depended upon its ability to 
discredit [the alleged accomplice], since his testimony was 
completely exculpatory.”  (Ibid.)  In such a context, an 
instruction that told the jury that that testimony could be used 
by itself to convict, but not to acquit, rose to the level of a due 
process violation and warranted reversal of the entire 
conviction.  Here, in contrast, the lone dog-trailing witness 
called by the defense testified for a few transcript pages, during 
the course of a guilt phase trial that lasted more than five 
months.  The failure of the modified version of CALJIC No. 2.16 
to tell the jury explicitly that it could acquit based on that scant 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
66 
 
absence-of-trailing evidence did not give rise to any comparable 
due process violation.19 
E. Admission of Expert Testimony Concerning the 
Trajectory of Conner’s Body in the San 
Francisco Bay 
Dr. Cheng, a senior research hydrologist for the United 
States Geological Survey, was called as an expert witness by the 
prosecution.  Dr. Cheng testified to his training, publications, 
and experience analyzing fluid dynamics, with a special focus on 
the San Francisco Bay.  The trial court accepted him as an 
expert hydrologist qualified to testify about the movement of 
water in the bay and related topics.  Dr. Cheng then described 
two analyses he did for the Modesto Police Department.  In 
February 2003, while Laci was still missing, Dr. Cheng 
analyzed where she might most likely be found based on an 
assumption given him by the police that Laci’s body had been 
placed in the bay in a particular area.  In May 2003, after Laci’s 
and Conner’s bodies were found, Dr. Cheng performed a second 
analysis to supply his best estimate concerning where they 
might have originated, and thus where divers should search for 
                                        
19  
Peterson makes one other argument — that the dog-
trailing evidence immediately followed a court instruction on 
motive that allowed the jury to consider the presence of a motive 
as weighing in favor of guilt and the absence of a motive as 
weighing in favor of acquittal, and a reasonable juror would 
have inferred from this sequence that by negative inference it 
was not permitted to consider dog-trailing evidence as 
supporting acquittal.  The motive instruction actually came 
after the dog-trailing evidence instruction, and, in any event, we 
do not read the dog-trailing instruction as reasonably 
susceptible to the understanding that jurors could not consider 
such evidence as supporting acquittal. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
67 
 
missing body parts and any weights or other evidence.  
Dr. Cheng offered his opinion that a particular region near 
Brooks Island represented the most likely starting point for 
Conner, but was unable to estimate any most likely origin for 
Laci. 
There is no dispute that Dr. Cheng’s training and 
experience qualified him as an expert in the area of fluid 
dynamics and, specifically, the flow of the waters of the San 
Francisco Bay.  Defense counsel conceded Dr. Cheng was 
qualified to give expert testimony on hydrology.  But during the 
Evidence Code section 402 hearing that preceded Dr. Cheng’s 
testimony, Peterson asked the court to require that foundation 
for Dr. Cheng’s testimony be laid under Kelly, supra, 17 Cal.3d 
24.  The court denied the request.  Peterson now contends 
Dr. Cheng’s opinions as to the movement of the victims’ bodies 
in the bay were inadmissible.  We review the decision to admit 
the expert testimony for abuse of discretion.  (People v. Banks 
(2014) 59 Cal.4th 1113, 1190.)  We conclude the court did not 
err. 
As discussed earlier, Kelly imposes certain preconditions 
on the admission of evidence derived from a novel scientific 
technique or procedure.  The additional scrutiny “is justified 
because ‘[l]ay jurors tend to give considerable weight to 
“scientific” evidence when presented by “experts” with 
impressive credentials. We have acknowledged the existence of 
a “. . . misleading aura of certainty which often envelops a new 
scientific 
process, 
obscuring 
its currently 
experimental 
nature.” ’ ”  (People v. Jones, supra, 57 Cal.4th at p. 952, quoting 
Kelly, supra, 17 Cal.3d at pp. 31–32.) 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
68 
 
But in most cases no similar caution is required before a 
jury considers expert opinion testimony.  Unlike results 
“produced by a machine,” to which jurors may “ascribe an 
inordinately high degree of certainty,” jurors presented with the 
personal opinion of a witness, even an expert witness, “may 
temper their acceptance of his [or her] testimony with a healthy 
skepticism born of their knowledge that all human beings are 
fallible.”  (People v. McDonald (1984) 37 Cal.3d 351, 372; accord, 
People v. Jones, supra, 57 Cal.4th at p. 953.)  For this reason, 
“ ‘[a]bsent some special feature which effectively blindsides the 
jury, expert opinion testimony is not subject to Kelly[].’ ”  (People 
v. Eubanks (2011) 53 Cal.4th 110, 140, quoting People v. Stoll 
(1989) 49 Cal.3d 1136, 1157.)  Of course, some expert testimony 
may be “based, in whole or part, on a technique, process, or 
theory which is new to science and, even more so, the law” (Stoll, 
at p. 1156); where the novel technique “appears in both name 
and description to provide some definitive truth which the 
expert need only accurately recognize and relay to the jury,” 
additional scrutiny under Kelly is warranted.  (Ibid.; see People 
v. Cowan (2010) 50 Cal.4th 401, 470.)  But this case does not fit 
that description. 
Dr. Cheng began with an overview for the jury of how 
various forces, including tides, currents, and wind, interact and 
affect the waters of the bay.  He then explained how, given the 
time and location where Conner’s body was found, he worked 
backward to estimate where Conner was most likely to have 
started.  Tidal currents in the area were weak and would likely 
have canceled out, so Dr. Cheng treated wind-driven drift as the 
principal force that would have moved Conner’s body to shore.  
He accepted as a starting assumption the hypothesis that Laci 
and Conner had been weighted down and then broken free and 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
69 
 
treated Conner as a floating body thereafter.  Performing 
calculations using an equation drawn from the United States 
Army Corps of Engineers Coastal Engineering Handbook to 
translate measured wind speeds into a corresponding rate of 
water movement, Dr. Cheng worked backward to estimate the 
most probable path Conner’s body would have followed. 
Dr. Cheng’s modeling involved no novel technique.  The 
study of tides and currents and their effect on the motion of 
bodies in water is hardly new.  Nor is the scientific 
understanding of how wind affects the movement of water — 
and thus bodies in water — of recent origin.  Indeed, as 
Dr. Cheng explained to the jury, much of his modeling involved 
applying established, published equations to the known 
conditions in the hours and days before Conner’s and Laci’s 
bodies were found.  The application of settled principles to 
estimate the motions of bodies in water did not require a Kelly 
hearing. 
While the absence of a novel technique alone disposes of 
Peterson’s Kelly argument (see People v. Stoll, supra, 49 Cal.3d 
at p. 1156), we also note that, as described by Dr. Cheng, the 
technique was not one that carried a “misleading aura of 
scientific infallibility” (id. at p. 1157) — the primary danger 
Kelly is designed to guard against.  Dr. Cheng apprised the jury 
of the ways in which the model’s accuracy was dependent on a 
host of initial assumptions, many of which carried with them a 
considerable degree of uncertainty.  For example, it was 
unknown when Conner’s body had actually washed ashore, 
which would have altered best estimates of his starting point, 
and no starting point could be estimated at all for Laci, who was 
found a day later at a point nearly one mile away from Conner.  
Moreover, because divers found no evidence to confirm Conner 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
70 
 
or Laci had ever been at the starting location Dr. Cheng 
suggested, the jury had ample basis to take his opinions with 
more than a dash of salt.20  Because Dr. Cheng’s testimony did 
not describe to the jury a mechanistic process that pointed 
unerringly to firm conclusions, it presented no risk of 
blindsiding the jury and precluding it from critically evaluating 
his ultimate opinion.  (See People v. Garlinger (2016) 247 
Cal.App.4th 1185, 1196–1197 [no risk jury would accord aura of 
infallibility to cell phone networks expert who “did not purport 
to be able to determine the precise location” of a cell phone].) 
Peterson relies heavily on People v. Leahy (1994) 8 Cal.4th 
587, but Leahy bears no resemblance to the case here.  There, 
police officers testified to the results of a “ ‘horizontal gaze 
nystagmus’ ” test purported to reliably indicate intoxication.  
(Id. at p. 605.)  We explained that the test was a “ ‘new’ ” 
technique for purposes of Kelly.  (Leahy, at p. 606.)  Further, 
with its “ ‘ “pretentiously scientific name,” ’ ” the test was one 
that might “appear[] to provide to the jury a ‘definitive truth.’ ”  
(Ibid.)  As such, the test involved the precise risk underlying the 
exception to the rule that expert testimony need not satisfy 
Kelly — it was a novel technique that “appears in both name and 
description to provide some definitive truth which the expert 
need only accurately recognize and relay to the jury.”  (People v. 
Stoll, supra, 49 Cal.3d at p. 1156.)  The same is not true of the 
methodology underlying Dr. Cheng’s testimony.  
                                        
20  
Indeed, recognizing that Dr. Cheng’s testimony might 
help the defense as much as it hurt, defense counsel said before 
Dr. Cheng testified, “[I]n some ways, I want it to come in 
because I believe his ultimate conclusion is that he can’t say 
anything about Laci.” 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
71 
 
Peterson also criticizes the extent of Dr. Cheng’s expertise 
as it relates to the motion of objects in fluids, as opposed to the 
motion of fluids themselves.  The criticism is not well taken.  For 
one, Dr. Cheng had a Ph.D. in aeronautical engineering and had 
studied the movement of drifters, devices used to measure 
currents at the surface and at depth.  For another, such 
criticisms go to the weight a jury might accord Dr. Cheng’s 
testimony, but not its admissibility or whether Kelly foundation 
was required.  (See People v. Eubanks, supra, 53 Cal.4th at 
p. 143.)  Peterson did, in fact, raise his concern about 
Dr. Cheng’s background during cross-examination, and the jury 
could consider that concern. 
In sum, Dr. Cheng, an expert hydrologist, could offer his 
opinion as to the most probable movement of Conner’s body in 
the San Francisco Bay without the court first conducting a Kelly 
hearing.  The court did not abuse its discretion in admitting his 
testimony. 
F. Issues Concerning the Stability of Peterson’s 
Boat 
1. Exclusion of Videotaped Defense Demonstration 
During the defense’s presentation of evidence, the court 
held an Evidence Code section 402 hearing to evaluate the 
admissibility of a videotaped experiment the defense had 
conducted from a boat on the San Francisco Bay.  In the 
experiment, an employee of defense counsel’s law firm tried to 
push a 150- to 155-pound dummy out of the boat.  The boat 
partially sank before the employee abandoned ship. 
The prosecution submitted a litany of objections.  From the 
videotape, it was not possible to determine the kind of boat used 
because identifying features had been covered up; the boat’s 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
72 
 
seats were mounted on wood, thus raising the boat’s center of 
gravity; the boat had a different motor than Peterson’s boat; the 
person performing the experiment was wearing a weight belt 
that impeded his movements; nothing established the prevailing 
tides, currents, and waves, or how closely they approximated the 
conditions on December 24, 2002; nothing established the 
location of the experiment; the boat’s gas tank and batteries 
were located in different positions than on Peterson’s boat; the 
boat had plywood decking added, which could affect its stability; 
the dummy got wet, which would have added weight; the boat 
was already starting to take on water before the employee even 
tried to dump the dummy; and the employee performed the 
experiment while standing on the boat’s gunwales, which 
suggested he was “intentionally trying to sink the boat.”  After 
reviewing the tape, the court ruled it inadmissible under 
Evidence Code section 352.  Peterson contends this was error. 
“ ‘Under Evidence Code section 352, the trial court has 
wide discretion to admit or reject experimental evidence.  We 
reverse decisions to admit or exclude such evidence only when 
the trial court has clearly abused its discretion.’ ”  (People v. 
Jones (2011) 51 Cal.4th 346, 375–376.)  Before experimental 
evidence may be admitted, the proponent must establish that 
the 
experiment 
is 
relevant, 
was 
“ ‘ “conducted 
under 
substantially similar conditions as those of the actual 
occurrence,” ’ ” and will not mislead or confuse the jury or take 
undue time.  (Jackson, supra, 1 Cal.5th at p. 342.) 
The prosecution raised a host of ways in which the defense 
did not carry its burden of establishing that its demonstration’s 
conditions sufficiently resembled conditions on December 24, 
2002.  The court could and did rely on these points, including 
Peterson’s failure to establish the similarity of the boat used, the 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
73 
 
weather, and the location.  From our own review of the proffered 
video, we cannot say the court abused its broad discretion to 
determine the video’s admissibility.  (See People v. Jones, supra, 
51 Cal.4th at pp. 375–376.)  The video shows the waters of the 
bay were extremely choppy during the experiment.  Even before 
the defense employee tried to hoist the dummy, the boat was 
taking on water because the employee was stepping on the 
boat’s gunwale, on the same side as an elevated seat (Peterson’s 
boat had no similar elevated seat) and the side toward which the 
boat’s roughly 75-pound motor had been angled.  This 
concentration of weight allowed waves to break over the boat’s 
gunwales.  However stable the boat might have been if attempts 
were made to counterbalance, no such attempts were made in 
the defense’s demonstration.  The boat also had plywood decking 
added, which would have not only raised the center of gravity, 
but also concealed whatever might have lain underneath. 
Peterson emphasized to the trial court that it had already 
admitted evidence of a prosecution experiment in which a 
district attorney’s office employee, also late in her third 
trimester of pregnancy and weighing the same as Laci, lay down 
in Peterson’s boat to show how someone could fit without being 
noticeable.  Peterson strenuously argued that, by parity of 
reasoning, his experiment should be admissible too.  He makes 
the same point on appeal.  But the two situations are not 
symmetric, and that asymmetry explains why a court could 
exercise its discretion to admit one experiment but not the other.  
As discussed, Peterson laid no foundation establishing the 
extent to which the conditions during his videotaped experiment 
mirrored those that would have obtained during the alleged 
disposal of the body.  In contrast, the prosecution’s photographs 
showed precisely the feasibility of what they posited had 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
74 
 
occurred — that the body of a pregnant, 153-pound woman could 
be curled to fit in the bottom of Peterson’s actual boat. 
The two experiments are asymmetric in a second way as 
well.  A person trying to dispose of a body by dumping it out of 
a boat into the bay would have had every incentive to 
counterbalance against the body’s weight in order to avoid 
capsizing the boat.  The defense firm’s employee, in contrast, 
had an incentive to undermine the experiment’s results, and 
indeed the prosecution argued that the video showed he was 
trying to do just that.  To be sure, the prosecution’s employee 
had an incentive to make herself fit, but that incentive does 
nothing to detract from the persuasive force of the prosecution’s 
experiment as evidence of the possible.  No matter how much 
the pregnant employee might have wanted to make the 
demonstration work, she could not have unless it was, in fact, 
possible for her to fit her body in that space.  As the court noted, 
“All she had to do was lay there.  She didn’t have to demonstrate 
throwing something — throwing something in the water.”   
Consequently, while the defense demonstration was not 
irrelevant, it was within the court’s discretion to conclude the 
defense had not laid sufficient foundation to establish the 
demonstration — conducted in a different boat, under different 
conditions, by a defense employee — bore a sufficiently close 
resemblance to how Peterson allegedly disposed of Laci’s body, 
so as to avoid misleading the jury.  That the trial court admitted 
photographs of the prosecution’s demonstration does not alter 
this conclusion. 
The refusal to admit the video was likewise not erroneous 
under federal law.  Peterson argues that the exclusion of the 
evidence violated his rights under the Fifth and Sixth 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
75 
 
Amendments to a fair trial and to submit evidence relevant to 
the question of guilt.  (See Pennsylvania v. Ritchie (1987) 480 
U.S. 39, 56; Chambers v. Mississippi (1973) 410 U.S. 284, 294.)  
Here, however, the court reasonably found the evidence to be 
unreliable and misleading.  The Constitution contains no right 
to admit such evidence. 
2. Conditions on Reprise of Defense Experiment 
In the course of ruling the defense’s boat experiment 
inadmissible, the court made clear it was not categorically 
barring any such experiment, only the experiment as originally 
conducted and submitted.  Counsel complained that the ruling 
gave the defense no way to oppose the prosecution’s case.  While 
cautioning that it was “not here to give you advice,” the court 
offered two ways in which the defense might choose to modify 
the experiment to increase its odds of admissibility:  “Number 
one, you take out the original boat instead of this boat.  [Number 
two, y]ou have someone that doesn’t work for you conduct the 
experiment, you know.  That would be two things that are out of 
the way.”  The court also suggested the defense try to establish 
what the conditions were like on the day Peterson was alleged 
to have dumped Laci’s body in the bay. 
Shortly after denying admission of the defense’s boat 
experiment, the court voluntarily revisited the issue and again 
made clear the defense could redo the experiment in a way that 
might make it admissible, if it so chose.  The court offered the 
defense access to Peterson’s boat to redo the experiment, adding 
“I think you should have representatives of the [P]eople there to 
observe what happens.”  Later, the court reiterated, “I’m willing 
to let you have the boat.  I’m willing to let you put the 150-pound 
person in it.  I’m willing to let you have somebody, but I want 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
76 
 
the prosecution to be present and watch the way this thing went 
down.  What’s wrong with that?”  The court also said it would be 
helpful if the reenactment included footage showing where 
Brooks Island was, relative to the demonstration, and was 
conducted in the general area the prosecution’s expert, 
Dr. Cheng, had suggested was most likely.  If the defense 
wanted to redo the experiment with some adjustments, the court 
offered to revisit its ruling.  Ultimately, Peterson elected not to 
redo the experiment. 
Peterson now contends that by offering to revisit its 
ruling, but conditioning access to the boat on the prosecution 
being able to observe any reenactment, the court committed 
presumptively prejudicial error compelling automatic reversal.  
Peterson has not preserved any claim of error. 
During the Evidence Code section 402 hearing on 
admissibility of the defense’s video and its aftermath, Peterson 
did not object to the trial court’s suggested condition, even as the 
court invited objection by asking, “What’s wrong with that?”  
Nor did Peterson move for the court to grant him access to the 
boat and to lift any condition that a member of the prosecution 
view experiments with that boat, or in any other way object to 
the court’s conditional offer of access to Peterson’s boat.  Instead, 
counsel thanked the court for its openness to revisiting its 
decision and said he would check the weather for suitable 
conditions and confer with his client. 
At the close of the Evidence Code section 402 hearing, 
then, here is where matters stood.  The defense had presented a 
video of a demonstration on the bay, and the court had — 
permissibly, as we have just discussed — exercised its discretion 
to exclude that video.  The court had also, sua sponte, made clear 
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Opinion of the Court by Kruger, J. 
 
77 
 
that its ruling did not foreclose a future attempt to videotape a 
further demonstration and resubmit a video for consideration.  
And finally, the court had suggested different ways the defense 
could modify the original experiment, if it so chose, including 
(1) using a different test subject, unaffiliated with the defense, 
to perform the experiment or (2) using the Peterson boat, with a 
prosecution observer.  Peterson did not object to the latter 
condition; he instead let the matter drop. 
The People argue that because Peterson elected not to 
conduct an experiment with the prosecution present, he has 
forfeited any claim on appeal.  This goes too far.  To preserve a 
claim that the court has unconstitutionally placed a condition 
on the defendant’s introduction of evidence, a defendant need 
not always comply with the condition.  (See, e.g., United States 
v. Nobles (1975) 422 U.S. 225 [addressing the merits after the 
defendant declined to comply with an allegedly unconstitutional 
condition and elected not to have a witness testify].)  But if the 
defendant objects to the condition, he does need to make his 
objection known (see, e.g., People v. Varghese (2008) 162 
Cal.App.4th 1084, 1090–1091), unless doing so would be futile 
(People v. Perez (2020) 9 Cal.5th 1, 7–8).  Here, nothing in the 
record suggests it would have been futile to raise the issue with 
the trial court.  It appears the trial court was merely throwing 
out ideas as to how the defense could redo the experiment in a 
way that would address the deficiencies of its first effort, not 
giving its final word on the subject. 
In this and other respects, this case differs from Prince v. 
Superior Court (1992) 8 Cal.App.4th 1176, 1179–1181, which 
held that a trial court could not condition the ability of the 
defense to test a critical DNA sample on disclosure of any results 
to the People.  Here, we do not know whether the trial court 
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Opinion of the Court by Kruger, J. 
 
78 
 
actually and finally conditioned the defense team’s ability to test 
the stability of the Peterson boat on the presence of a 
prosecution observer, because Peterson never raised any 
concerns about the trial court’s offer to revisit its exclusion 
ruling under those circumstances.  Had the court said nothing 
at all after excluding the original, flawed demonstration, 
Peterson would have no argument.  That the court volunteered 
one way in which Peterson could rectify the problems with the 
original demonstration did not inject constitutional error into 
the proceedings, let alone presumptively prejudicial error 
compelling automatic reversal. 
3. Prosecutorial Misconduct in Closing Argument 
During closing argument, the prosecution addressed the 
stability of Peterson’s boat.  According to the prosecutor, 
although the defense had insinuated a boat like his was “ready 
to tip over at the drop of a hat” and would have capsized if 
Peterson had tried to push Laci’s body overboard, “there’s no 
evidence [the boat] would have done that.”  He recounted the 
testimony of prosecution witnesses indicating the boat was 
stable enough to pull heavy fish on or push heavy weights off 
and concluded, “There’s no evidence to contradict that 
whatsoever.”  Peterson argues these comments were reversible 
misconduct because they improperly took advantage of the 
exclusion of the defense’s evidence about the boat’s instability.  
We disagree; this was not misconduct. 
“Prosecutorial misconduct requires reversal when it ‘so 
infect[s] a trial with unfairness [as to] create a denial of due 
process.  [Citations.]  Conduct by a prosecutor that does not 
reach that level nevertheless constitutes misconduct under state 
law, but only if it involves the use of deceptive or reprehensible 
PEOPLE v. PETERSON 
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79 
 
methods to persuade the court or jury.’ ”  (People v. Armstrong, 
supra, 6 Cal.5th at p. 795.) 
Preliminarily, Peterson has forfeited his claim that the 
prosecutor engaged in prejudicial misconduct.  To preserve a 
claim for review, a defendant must object and ask that the jury 
be admonished concerning the misconduct.  (People v. Daveggio 
and Michaud (2018) 4 Cal.5th 790, 853; People v. Bryant, Smith 
and Wheeler (2014) 60 Cal.4th 335, 426–427; People v. Watkins 
(2012) 55 Cal.4th 999, 1031.)  Peterson concedes he did not 
object, but contends objection was excused because prosecutors 
are held in such high regard that no admonishment from a court 
could cure any harm.  If Peterson were correct, then no criminal 
defendant would ever need object to perceived prosecutorial 
misconduct.  The case law is, of course, to the contrary.  (See 
People v. Panah (2005) 35 Cal.4th 395, 462 [“A defendant 
claiming that one of these exceptions [to the objection 
requirement] applies must find support for his or her claim in 
the record.  [Citation.]  The ritual incantation that an exception 
applies is not enough.”].)  Alternatively, Peterson argues that 
counsel was ineffective for failing to object.  But counsel’s 
performance was not deficient; any such objection would have 
been meritless and properly overruled. 
As the record stood at the close of the guilt phase, there 
was, in fact, no evidence affirmatively supporting the argument 
that Peterson’s boat was too unstable for Peterson to have 
thrown Laci off it.  Peterson cross-examined the prosecution’s 
witnesses in an attempt to cast doubt as to whether their 
testimony adequately established the boat’s stability.  But 
Peterson introduced no evidence of instability to contradict that 
testimony.  The prosecution’s observations about this omission 
were thus fair comment on the state of the evidence. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
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Peterson does not contend otherwise, but instead urges 
that the only reason the record contains no such evidence is that 
the 
prosecution 
moved, 
successfully, 
to 
exclude 
the 
aforementioned video of the defense’s demonstration in which a 
surrogate boat capsized.  In Peterson’s view, it was misconduct 
for the prosecution to obtain the exclusion of evidence and then 
comment on the resulting evidentiary vacuum. 
That is not the law, as we explained in People v. Lawley 
(2002) 27 Cal.4th 102 (Lawley).  In Lawley, the defendant sought 
to introduce evidence of third party culpability, but the court 
excluded it at the prosecution’s urging — a ruling we upheld as 
correct.  (Id. at pp. 151–155.)  The prosecutor then argued in 
closing that no one but the defendant had a motive to kill the 
victim.  The defendant urged this as misconduct, but we 
explained that, in light of the court’s correct evidentiary rulings, 
the prosecution’s argument was fair comment on the record as 
it stood.  (Id. at p. 156.)  Lawley makes clear that it is not 
misconduct for the prosecutor to argue in closing that there was 
no evidence supporting a particular proposition after the trial 
court has properly excluded evidence the defense had sought to 
introduce on that point. 
Peterson relies on other cases, but they do not establish 
that the prosecution is barred from ever remarking on an 
evidentiary gap after successfully moving to exclude evidence 
that would have filled that gap.  The only two California cases 
he cites, People v. Daggett (1990) 225 Cal.App.3d 751 and People 
v. Varona (1983) 143 Cal.App.3d 566, were likewise invoked by 
the defendant in Lawley; we distinguished them as “inapposite” 
because “each involved erroneous evidentiary rulings on which 
the prosecutor improperly capitalized during his closing 
argument.”  (Lawley, supra, 27 Cal.4th at p. 156, italics added.)  
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
81 
 
Here, by contrast, there was no error in the exclusion of the 
evidence.21 
Peterson’s cases from other jurisdictions are likewise 
distinguishable because each involved erroneously excluded 
evidence or a prosecutor deceiving the jury into making 
inferences the prosecutor knew to be untrue.  (Cf. Paxton v. 
Ward (10th Cir. 1999) 199 F.3d 1197 [prosecution misled the 
jury as to the reason charges against the defendant for a prior 
shooting had been dropped]; U.S. v. Ebens (6th Cir. 1986) 800 
F.2d 1422 [reversal required where the prosecution suggested to 
the jury inferences it knew to be untrue]; U.S. v. Toney (6th Cir. 
1979) 599 F.2d 787 [erroneous exclusion of evidence 
corroborating the defendant’s story prejudicial because the 
prosecution stressed the absence of corroborating evidence]; 
State v. Bass (1996) 121 N.C.App. 306 [465 S.E.2d 334] 
[prosecution argued inference to the jury that it knew to be 
untrue].)  These cases involved “ ‘deceptive or reprehensible 
methods to persuade the court or jury.’ ”  (People v. Armstrong, 
supra, 6 Cal.5th at p. 795.)  Here, instead, the prosecutor 
commented fairly on the record.  There was no misconduct. 
                                        
21  
Our recent decision in People v. Armstrong, supra, 6 
Cal.5th 735, is similarly distinguishable.  There, we found 
misconduct after a prosecutor persuaded the trial court to 
exclude defense evidence of what the victim said before she was 
attacked — evidence that should have been admitted — and 
then attributed to the victim a different statement nowhere 
supported in the record.  (Id. at pp. 785–787, 796–797.)  The 
prosecutor here, in contrast, commented only on the admissible 
evidence and did so accurately. 
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4. Juror Examination of the Physical Evidence During 
Deliberations 
Peterson’s boat was admitted into evidence.  During trial, 
the jury was given the opportunity to inspect it.  During 
deliberations, the jurors asked to look at the boat again.  The 
court agreed and had them do so with the prosecution and 
defense present.  Some jurors asked to sit in the boat.  The court 
acquiesced, reasoning that they should be permitted to test for 
themselves the evidence the prosecution had submitted 
concerning how a person (or body) could fit in the bottom of the 
boat.  While in the boat, at least two jurors stood and, by shifting 
their weight back and forth, rocked the boat.  The court 
cautioned the jurors that they should keep in mind the boat was 
secured on a trailer, not in the water.  Peterson argued that the 
jurors’ attempts to rock the boat constituted an impermissible 
experiment and sought an opportunity to reopen the evidence 
and submit his excluded boat demonstration or, in the 
alternative, a mistrial.  The court denied both motions. 
Peterson argues the denial of a mistrial based on juror 
experimentation violated both state and federal law.  The denial 
of a motion for a mistrial is generally reviewed for abuse of 
discretion.  (People v. Bell (2019) 7 Cal.5th 70, 121.)  Where, 
however, the motion rests on allegations of juror misconduct and 
the 
facts 
underlying 
those 
allegations 
are 
essentially 
undisputed, we review de novo whether misconduct occurred.  
(People v. Collins (2010) 49 Cal.4th 175, 242 (Collins).)  There 
was no misconduct, and thus no error in denying the motion for 
a mistrial. 
The 
framework 
for 
analyzing 
whether 
jury 
experimentation is permissible or misconduct was established 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
83 
 
more than a century ago in Higgins v. L.A. Gas & Electric Co. 
(1911) 159 Cal. 651, 656–657 (Higgins):  “It is a fundamental 
rule that all evidence shall be taken in open court and that each 
party to a controversy shall have knowledge of, and thus be 
enabled to meet and answer, any evidence brought against him.  
It is this fundamental rule which is to govern the use of such 
exhibits by the jury.  They may use the exhibit according to its 
nature to aid them in weighing the evidence which has been 
given and in reaching a conclusion upon a controverted matter.  
They may carry out experiments within the lines of offered 
evidence, but if their experiments shall invade new fields and 
they shall be influenced in their verdict by discoveries from such 
experiments which will not fall fairly within the scope and 
purview of the evidence, then, manifestly, the jury has been 
itself taking evidence without the knowledge of either party, 
evidence which it is not possible for the party injured to meet, 
answer, or explain.” 
We reviewed these principles and endorsed them anew in 
Collins, supra, 49 Cal.4th at pages 243 to 249.  After discussing 
Higgins, the cases it relied on, and the many cases that had 
followed it, we elaborated on the guiding principles:  “Not every 
jury experiment constitutes misconduct.  Improper experiments 
are those that allow the jury to discover new evidence by delving 
into areas not examined during trial.  The distinction between 
proper and improper jury conduct turns on this difference.  The 
jury may weigh and evaluate the evidence it has received.  It is 
entitled to scrutinize that evidence, subjecting it to careful 
consideration by testing all reasonable inferences.  It may 
reexamine the evidence in a slightly different context as long as 
that evaluation is within the ‘ “scope and purview of the 
evidence.” ’  [Citation.]  What the jury cannot do is conduct a 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
84 
 
new investigation going beyond the evidence admitted.”  
(Collins, at p. 249.) 
The propriety of the jurors’ rocking the boat thus turns on 
whether they were merely scrutinizing the evidence admitted on 
a question joined at trial, or instead “invad[ing] new fields” that 
lay outside the “scope and purview of the evidence.”  (Higgins, 
supra, 159 Cal. at p. 657.)  The question of the boat’s stability 
was already contested, and evidence had been submitted on this 
very question.  The boat itself was admitted into evidence.  
Rocking the boat to get some rough sense of its stability did not 
expand the issues in the case or amount to a taking of new 
evidence on a previously unexamined question — although, to 
be clear, the information to be gleaned from assessing the boat’s 
stability on land, on a trailer, as opposed to in water, was likely 
minimal. 
Peterson invokes a number of cases finding impermissible 
experimentation, 
but 
these 
cases 
generally 
involved 
experiments with items outside the scope of the evidence in the 
case.  In Smoketree-Lake Murray, Ltd. v. Mills Concrete 
Construction Co. (1991) 234 Cal.App.3d 1724, 1745–1749, a 
juror used kitty litter and crayons to model the pouring of 
concrete.  In People v. Castro (1986) 184 Cal.App.3d 849, 852–
854, a juror used an entirely different pair of binoculars to 
determine whether a witness who used binoculars could have 
seen what he testified to seeing.  In People v. Conkling (1896) 
111 Cal. 616, 627–628, jurors used a rifle other than the murder 
weapon to conduct tests on the distance at which powder marks 
would show.  And in Bell v. State of California (1998) 63 
Cal.App.4th 919, 930–933, after the plaintiff claimed he had 
been falsely arrested, placed in an awkward hold, and forced to 
walk, a juror tested whether one could walk in the manner 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
85 
 
described by trying to recreate the hold using different people of 
different size, strength, and so on.  Peterson also relies on 
Wilson v. U.S. (9th Cir. 1902) 116 F. 484, cited with approval in 
Higgins, supra, 159 Cal. at pages 657 to 658, but that case holds 
only that it is misconduct to investigate questions on which no 
evidence at all has been submitted.  That is not the case here. 
This case shares far more in common with People v. 
Cumpian (1991) 1 Cal.App.4th 307, in which an issue in the case 
was how difficult it would have been for the defendant to remove 
a duffel bag he had strapped to his body.  The actual duffel bag 
was admitted into evidence and several jurors put it on as the 
defendant had described and then tried to remove it.  (Id. at 
pp. 310–311.)  This was not misconduct:  “To prohibit jurors 
from analyzing exhibits in light of proffered testimony would 
obviate any reason for sending physical evidence into the jury 
room in the first instance.”  (Id. at p. 316.) 
“Nothing requires that the jury’s deliberations be entirely 
verbal, and we would expect a conscientious jury to closely 
examine the testimony of the witnesses, no less so when that 
testimony takes the form of a physical act.”  (People v. Cooper 
(1979) 95 Cal.App.3d 844, 854.)  When physical exhibits are 
admitted into evidence and supplied to the jury, they may 
examine and manipulate the exhibits to assess propositions 
placed at issue, and upon which evidence has been submitted, 
during the trial.  (E.g., People v. Baldine (2001) 94 Cal.App.4th 
773, 777–780 [jurors could test whether police scanner, 
admitted into evidence, worked, after the defendant testified it 
did not]; People v. Bogle (1995) 41 Cal.App.4th 770, 778–781 
[permissible for jurors to test whether the defendant’s keys, 
admitted into evidence, opened a safe, also admitted into 
evidence]; see People v. Singh (2012) 206 Cal.App.4th 366, 373 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
86 
 
[“Manipulation of an exhibit in evidence does not constitute 
receipt of new evidence” and is “a legitimate part of 
deliberations”].)  
When jurors tried to rock Peterson’s boat to assess its 
stability, they did no more than manipulate a physical exhibit 
admitted into evidence at trial.  Their movements did not result 
in the impermissible receipt of extrinsic evidence.  Moreover, 
and in any event, the court’s cautionary instruction helpfully 
ensured jurors would consider material differences between the 
setting in which they were permitted to examine the physical 
evidence — on land, on a trailer — and the setting in which the 
boat’s stability was at issue — on the San Francisco Bay, under 
the weather conditions of December 24, 2002. 
Because there was no misconduct, it was not an abuse of 
discretion to deny Peterson’s motion for a mistrial, nor were 
Peterson’s rights to trial by an impartial jury infringed. 
G. Other Juror Misconduct Issues 
1. Dismissal of Juror No. 5 
During the guilt phase trial, the court excused a juror for 
discussing the case with others, contrary to the court’s 
admonition.  Peterson contends this was error or, in the 
alternative, that the court should have excused other jurors as 
well, and that the decision to excuse one juror and not others 
violated his statutory and constitutional rights to trial by an 
impartial jury.  (U.S. Const., 5th & 6th Amends.; Pen. Code, 
§ 1089.)  The trial court did not abuse its discretion, and 
Peterson was not denied an impartial jury. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
87 
 
a. Background 
Three weeks into trial, the court’s bailiff received 
information from multiple jurors that Juror No. 5 was 
discussing the evidence with others over the objections of jurors 
who had asked him to stop and in contravention of the court’s 
daily admonitions to the jury to not discuss the case until after 
closing argument.  To investigate the allegations, the court 
questioned every member of the jury individually, in chambers 
and under oath, beginning with Juror No. 5. 
Specific written allegations from one juror included claims 
that Juror No. 5 had commented on the homemade boat anchor 
introduced as a prosecution exhibit, testimony from prosecution 
witness Detective Brocchini, Laci’s pregnancy weight gain, the 
sufficiency of reports prepared by the Modesto Police 
Department, deficiencies in the prosecution’s presentation, and 
how the juror was being portrayed in the media.  When called in 
to court to testify, Juror No. 5 initially denied the allegations 
were true but then agreed that “general conversations” about 
some of these topics might have occurred.  Describing the anchor 
conversation, he said that a juror had wondered about the 
anchor’s weight, and in response he had discussed his own 
experience using anchors when fishing.  Juror No. 5 denied 
commenting 
on 
Detective 
Brocchini’s 
testimony, 
the 
prosecution’s presentation, or Laci’s weight but said comments 
about her weight had been made by others.  His response to 
being called a “loose cannon” and other names by commentators 
on a cable network covering the trial, Court TV, was “keep them 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
88 
 
coming.”22  It was other jurors, not Juror No. 5, who had 
discussed the need for detail and accuracy in official filed 
reports.   
Juror No. 8, who had submitted the confidential letter to 
the court, was sworn and supplemented its contents.  He 
affirmed that Juror No. 5 spoke constantly about the facts and 
issues in the case, even after the court’s admonishment that the 
jurors not do so.  He reported that the previous day, Juror No. 5 
had discussed the anchor introduced into evidence and had said 
it could not anchor a boat as big as Peterson’s because of the 
strength of the currents in the San Francisco Bay.  Juror No. 5 
had said that in his opinion Detective Brocchini’s testimony 
raised many questions.  After evidence was introduced that 
Laci’s weight had increased from 126 pounds to 153 pounds 
during pregnancy, Juror No. 5 had opined that she might have 
been more than eight months pregnant.  He had said, based on 
his work experience filing reports, that the Modesto Police 
Department should have done a better job.  Juror No. 5 had 
commented on “[m]ore than one occasion” that the prosecution’s 
presentation left “a little to be desired.”  Finally, Juror No. 5 had 
never said he personally watched Court TV, but when his 
girlfriend relayed that he was being described by them as “a 
loose cannon,” he had said, “Well, I sort of pride myself on that.”  
Juror No. 8 had twice personally confronted Juror No. 5 to ask 
him to stop but had given up because it hadn’t worked, despite 
                                        
22  
Media coverage of the Peterson trial was sufficiently 
intense that perceived interactions (both verbal and nonverbal) 
between various jurors and members of the defense and 
prosecution as they entered and exited the courtroom became 
the subject of ongoing comment in the press and on television. 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
89 
 
Juror No. 5’s statements that “[i]f anyone has a problem with 
this, they should be man enough to come up to [me].”   
Every juror was questioned.  Some jurors had not heard 
any of what Juror No. 8 reported, but others confirmed either 
comments Juror No. 5 had made or more generally that these 
topics had been discussed.  Alternate Juror No. 2 admitted 
having asked about the anchor’s weight and being assured it 
could be examined during deliberations.  Jurors No. 7 and No. 9 
confirmed a conversation about fishing and anchors had taken 
place, although they could not be certain of the source.  Juror 
No. 4 affirmed that there had been discussion concerning the 
weight of the anchor, though he too was unsure of the source.  
Other jurors were able to specifically attribute comments to 
Juror No. 5:  Juror No. 6 said Juror No. 5 had discussed how 
currents can pull a boat’s anchor, and Alternate Juror No. 6 
heard Juror No. 5 say the anchor in the case was smaller than 
anticipated, too small to anchor a boat like Peterson’s. 
Concerning Detective Brocchini, Juror No. 6 said someone 
had commented that Detective Brocchini was “[g]etting a 
reaming” on cross-examination, and Juror No. 4 said Juror 
No. 5 had asked him if he got anything out of Detective 
Brocchini’s testimony.  Juror No. 6 said Juror No. 5 had made 
remarks about the Modesto Police Department, though he could 
not recall the content, and had said the prosecution did not seem 
organized.  Juror No. 3 likewise reported that Juror No. 5 had 
commented on the prosecutors’ presentation.  Alternate Jurors 
No. 5 and No. 6 heard discussions of the prosecution’s and 
defense’s presentations, though they could not say whether 
Juror No. 5 had participated.  Juror No. 2 and others told Juror 
No. 5 he should not be discussing the case, while Alternate Juror 
No. 3 overheard another juror remind Juror No. 5 they shouldn’t 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
90 
 
discuss the case after a comment he made.  Lastly, most jurors 
had heard Juror No. 5 discuss his portrayal as a loose cannon in 
the media and how he was being negatively portrayed on Court 
TV. 
In light of this testimony, defense counsel urged that Juror 
No. 5 be retained but the entire panel given a stern lecture.  In 
the alternative, if Juror No. 5 were to be excused, others who 
had talked with him about the case should be excused too.  The 
prosecution argued that Juror No. 5 had repeatedly ignored the 
court’s instructions not to discuss the case and should be 
removed. 
Over defense objection, the court discharged Juror No. 5.  
It concluded that Juror No. 8 was more credible than Juror 
No. 5, that Juror No. 5 had disregarded the instruction not to 
discuss the facts of the case, and that he likely would continue 
to do so.  In the court’s opinion, based on the testimony received, 
Juror No. 5 was “a total cancer [on] this jury” who could not be 
allowed to remain. 
b. Discussion 
Under Penal Code section 1089, “[i]f at any time, whether 
before or after the final submission of the case to the jury, a juror 
dies or becomes ill, or upon other good cause shown to the court 
is found to be unable to perform his or her duty, . . . the court 
may order the juror to be discharged and draw the name of an 
alternate” to replace the discharged juror.  A failure to follow the 
court’s instructions is misconduct and a basis for dismissal.  
(People v. Williams (2015) 61 Cal.4th 1244, 1262; People v. 
Linton (2013) 56 Cal.4th 1146, 1194.)  This extends to the 
obligation not to discuss a case prematurely.  Courts are 
required to instruct jurors not to discuss any aspect of a case 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
91 
 
amongst themselves before beginning deliberations (Pen. Code, 
§ 1122),23 and the court followed that directive here, instructing 
the jury before opening statements and at each adjournment to 
refrain from discussing the case.  (See CALJIC No. 0.50; 
CALCRIM No. 101.24)  “A juror’s violation of these directions 
constitutes serious misconduct.”  (Williams, at p. 1262; see 
People v. Sandoval (2015) 62 Cal.4th 394, 437; People v. 
Weatherton (2014) 59 Cal.4th 589, 599 & fn. 10; People v. 
Ledesma (2006) 39 Cal.4th 641, 743; People v. Daniels (1991) 52 
Cal.3d 815, 863–866.) 
“ ‘The . . . ultimate decision whether to retain or discharge 
a juror . . .  rests within the sound discretion of the trial court.’ ”  
(People v. Sattiewhite (2014) 59 Cal.4th 446, 486; see People v. 
Williams, supra, 61 Cal.4th at p. 1262.)  “ ‘In determining 
whether juror misconduct occurred, “[w]e accept the trial court’s 
credibility determinations and findings on questions of 
historical fact if supported by substantial evidence.” ’ ”  (People 
v. Linton, supra, 56 Cal.4th at p. 1194; see People v. Nesler 
(1997) 16 Cal.4th 561, 582.)  We will uphold the trial court’s 
decision if the record supports the basis for that decision as a 
“ ‘demonstrable reality.’ ”  (Williams, at p. 1262.)  This means 
simply that the record must reveal the reason for the court’s 
                                        
23  
Under Penal Code section 1122, subdivision (a)(1), a court 
must admonish the jury before opening statements not to 
“converse among themselves, or with anyone else . . . on any 
subject connected with the trial.”  Under subdivision (b), the 
court must repeat this admonishment at every adjournment 
until the case is submitted to the jury. 
24  
After the jurors were sworn, they were instructed, in the 
language of CALJIC No. 0.50, that “[y]ou must not converse 
among yourselves or with anyone else on any subject connected 
with this trial” except when deliberating.   
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
92 
 
decision to discharge a juror and in turn substantial evidence 
must support that reason.  (People v. Duff (2014) 58 Cal.4th 527, 
560.)  So long as it does, “ ‘the court’s action will be upheld on 
appeal.’ ”  (Sattiewhite, at p. 486.) 
Here, Juror No. 8 testified that Juror No. 5 violated the 
directive not to discuss any aspect of the case on multiple 
occasions and in connection with multiple topics.  Other jurors 
corroborated aspects of that testimony.  Although Juror No. 5 
largely denied discussing the case with others, the court credited 
Juror No. 8’s testimony over that of Juror No. 5.  The court 
concluded, after hearing from every juror, that Juror No. 5 had 
violated the instruction not to discuss the case and could not be 
trusted to refrain from doing so in the future, and on that basis 
discharged Juror No. 5.  Substantial evidence — specifically, the 
testimony of the many other jurors who heard Juror No. 5 
discuss aspects of the case — supports that conclusion. 
Peterson acknowledges Juror No. 5 engaged in misconduct 
by disregarding the court’s admonition not to discuss the case.  
He nevertheless urges that the court’s decision to excuse the 
juror was an abuse of discretion.  We disagree. 
Peterson’s argument depends on crediting Juror No. 5’s 
own report minimizing the significance of his actions.  It 
disregards both the contrary testimony of Juror No. 8 and the 
portions of other jurors’ statements that corroborated that 
testimony.  We are not free to do the same.  The trial court made 
an express credibility finding, siding with Juror No. 8’s version 
of events over Juror No. 5’s version:  “I have the testimony of 
Juror Number 8, and I’m more inclined to believe Juror Number 
8 than I am to believe Juror Number 5.”  That finding rested in 
part on the court’s observation of these jurors as they testified: 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
93 
 
“I’m satisfied by watching [Juror Number 5’s] demeanor, and 
watching the demeanor of Juror Number 8 and some of these 
other [jurors].”  The court was able to observe matters not 
evident from the cold appellate record — and what the record 
does show is generally supportive of the court’s conclusion.  
Here, for example, the prosecutor commented that when Juror 
No. 5 was confronted with the accusations, the hesitation he 
gave before issuing a denial was “the longest pause I’ve ever 
seen.”  The court did not disagree.  Such considerations may play 
a central role in evaluating credibility and underlie the 
requirement that appellate courts defer to such assessments 
when they find any support in the record.  (See People v. 
Williams, supra, 61 Cal.4th at p. 1262 [“We defer to the trial 
court’s credibility assessments ‘based, as they are, on firsthand 
observations unavailable to us on appeal’ ”].)  We accept the 
court’s determination that Juror No. 5 was being less than fully 
truthful, a determination the court could rely on in deciding to 
excuse the juror.  (See id. at pp. 1261–1263.) 
People v. Wilson (2008) 44 Cal.4th 758, on which Peterson 
heavily relies, is distinguishable.  There, a juror on one occasion 
made “solitary and fleeting comments” to another juror.  (Id. at 
p. 839.)  We determined this violation of the court’s admonition 
“was a trivial one:  one, possibly two sentences, spoken in 
rhetorical fashion and not in an obvious attempt to persuade 
anyone.”  (Id. at pp. 839–840.)  Only one other juror even heard 
the remark, and did not respond.  Nor did the substance of the 
remarks — “ ‘this is what happens when you have no authority 
figure’ ” (id. at p. 836) — suggest prejudgment of the appropriate 
penalty, as the trial court had found (id. at pp. 840–841).  Here, 
in contrast, the court received testimony under oath that in the 
first three weeks of trial, Juror No. 5 had discussed aloud the 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
94 
 
effectiveness of the prosecution’s presentation of evidence, the 
cross-examination of one of its witnesses, inferences to be drawn 
from Laci’s weight gain, the usefulness of a boat anchor 
admitted into evidence, and other case-related topics. 
More analogous is People v. Williams, supra, 61 Cal.4th 
1244, where a juror was overheard offering her opinion as to 
which witnesses were telling the truth.  Although only one other 
juror recalled the statement, the court could credit that juror, 
disbelieve the first juror’s denial, and discharge her based on her 
willingness to prejudge matters, discuss the prejudgment aloud, 
and conceal her misconduct.  (Id. at pp. 1260–1263.)  Here, as 
there, the court could credit Juror No. 8’s testimony over that of 
Juror No. 5 and conclude Juror No. 5 could not be trusted going 
forward. 
In the alternative, Peterson argues that if it was 
permissible for the court to discharge Juror No. 5, then it was 
an abuse of discretion not to simultaneously excuse other jurors 
Juror No. 5 talked to, including Jurors No. 4 and No. 6 and 
Alternate Jurors No. 2 and No. 6.  But Juror No. 5 was different 
from these others in at least two material respects.  First, the 
court heard testimony from Juror No. 8, whom it credited, that 
Juror No. 5 was “the leader of the clique” of jurors who talked 
about the case and the one who “usually starts the 
conversation.”  In other words, Juror No. 5 was not simply a 
participant, but an instigator.  Second, Juror No. 5 was alone 
among the jurors in denying participation in conversations in a 
way the court found less than credible.  Based on these 
considerations, the trial court concluded “this guy is not 
following the Court’s admonitions” and, going forward, “[h]e’s 
not about to follow the Court’s admonitions.”  The court viewed 
Juror No. 5, specifically, as “a cancer in that jury room” whom it 
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Opinion of the Court by Kruger, J. 
 
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could not trust to follow the court’s instructions and someone 
who, if left on the jury, seemed likely to supply grounds for a 
new trial motion down the road.  Where, as here, the record 
supplies evidence that a juror cannot be trusted to follow the 
court’s instructions going forward, the court may discharge the 
juror.  (See People v. Williams, supra, 61 Cal.4th at pp. 1262–
1263; People v. Daniels, supra, 52 Cal.3d at p. 865 [“a judge may 
reasonably conclude that a juror who has violated instructions 
to refrain from discussing the case . . . cannot be counted on to 
follow instructions in the future”].) 
Peterson’s 
brief, 
undeveloped 
claims 
of 
federal 
constitutional error arising from the dismissal of Juror No. 5 
rest on the principle, established in Witherspoon, supra, 391 
U.S. 510 and Adams v. Texas, supra, 448 U.S. 38, that the right 
to trial by an impartial jury may be compromised when a state 
selectively culls jurors able to consider the facts and faithfully 
apply the law.  But Adams and Witherspoon both involved the 
selective removal of prospective jurors on an entirely different 
basis — namely, their generally unfavorable views of the death 
penalty.  Neither those cases nor any other authorities establish 
the proposition that the constitutional right to a jury trial 
constrains a court from removing sitting jurors who fail or refuse 
to follow the court’s instructions. 
2. Failure to Adequately Investigate Allegations of 
Misconduct by Juror No. 8 
Before the start of the penalty phase trial, the court 
received information that Juror No. 8 had discussed the case 
with others and the jury had predetermined Peterson should be 
sentenced to die.  The court held an evidentiary hearing, 
concluded the allegations were unfounded, and denied 
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Opinion of the Court by Kruger, J. 
 
96 
 
Peterson’s motion for a mistrial.  Peterson now argues that the 
hearing preceding that ruling was inadequate.  Because 
Peterson made no objection, the argument is forfeited.  On the 
merits, Peterson has not shown an abuse of discretion. 
a. Background 
After the conclusion of the guilt phase trial and before the 
beginning of the penalty phase trial, the San Mateo District 
Attorney’s Office received a call from a local attorney concerning 
Juror No. 8.  The tipster relayed conversations she had had with 
a neighbor, Gino Gonzalez, who was a bartender.  Gonzalez 
reportedly said Juror No. 8 frequented his bar, and Gonzalez 
had learned that the jury kept secret notebooks and had already 
decided to impose the death penalty.  The attorney 
acknowledged that her report involved “ ‘multiple [levels of] 
hearsay.’ ” 
At the court’s request, the investigator who received the 
call followed up directly with Gonzalez.  Gonzalez said the 
attorney’s report was “ ‘ridiculous and not true in any sense.’ ”  
Gonzalez knew Juror No. 8 and that he was on a jury in an 
unspecified high-profile case, but had never heard Juror No. 8 
discuss which case it was or anything about the case. 
The court held a hearing and had the tipster attorney 
testify.  She described the circumstances and affirmed the 
content of her conversations with Gonzalez but acknowledged 
that she did not know whether Gonzalez had gotten his 
information directly from Juror No. 8 or from Juror No. 8’s 
girlfriend, who worked with Gonzalez.  She added that Gonzalez 
reported serving beer to Juror No. 8 in the morning, after the 
juror came in following a night shift and before he went to court.   
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Opinion of the Court by Kruger, J. 
 
97 
 
Gonzalez appeared through a lawyer, who represented 
that Gonzalez would invoke the Fifth Amendment if called to 
testify unless granted immunity.  Gonzalez’s attorney also 
represented that, if questions were limited to whether Gonzalez 
had spoken with Juror No. 8, he would answer, and would say, 
consistent with the investigator’s report, that Juror No. 8 had 
never revealed any more than that he was a juror in a high-
profile case.  The court elected not to call Gonzalez, and instead 
to question each juror and alternate concerning whether they 
had discussed or predetermined their penalty verdict.  Peterson 
did not object.   
When called, every juror denied discussing the penalty to 
be imposed or reaching a premature decision on the question.  
Juror No. 8 additionally denied drinking before coming to court, 
conversing with Gonzalez or anyone else at his bar about the 
case, or saying to anyone that the jury kept secret notebooks.   
Based on this testimony, the court concluded the jury had 
not predetermined the penalty verdict and denied Peterson’s 
motion for a mistrial. 
b. Discussion 
“A trial court learning of grounds for dismissal [of a juror] 
‘has an affirmative obligation to investigate.’  [Citation.]  
However, ‘[b]oth the scope of any investigation and the ultimate 
decision whether to discharge a given juror are committed to the 
sound discretion of the trial court.’ ”  (People v. Duff, supra, 58 
Cal.4th at p. 560; see People v. Manibusan (2013) 58 Cal.4th 40, 
53–54.)  Hearsay evidence of “alleged jury misconduct ordinarily 
is insufficient to establish an abuse of discretion in either 
denying the motion [for a mistrial based on misconduct] or 
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Opinion of the Court by Kruger, J. 
 
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declining to conduct an evidentiary hearing.”  (Manibusan, at 
p. 55.) 
Here, the court had before it only the tipster attorney’s 
testimony about hearsay statements by Gonzalez to her and 
Gonzalez’s hearsay denial of those statements.  It could have 
called Gonzalez to testify but chose not to given Gonzalez’s 
insistence on invoking the Fifth Amendment absent a grant of 
immunity from prosecution.  Instead, the court elected to go 
directly to the jury and ask each juror whether discussions or 
prejudgment of the penalty had occurred.  If Peterson disagreed 
with this course of action, it was incumbent on him to object at 
the time and give the court the opportunity to correct any 
perceived error. 
Peterson did not.  Quite to the contrary, defense counsel 
asserted that, if granted immunity and called to testify, 
Gonzalez would surely just say any statements attributed to 
him by the attorney were untrue.  Counsel thus backed down 
from an earlier request that the parties be sent to the presiding 
judge and afforded an opportunity to seek immunity for 
Gonzalez, apparently concluding that such proceedings would 
be unhelpful in light of Gonzalez’s anticipated testimony.  
Indeed, when the court obtained from Gonzalez’s counsel an 
agreement to appear and answer questions limited to whether 
Gonzalez and Juror No. 8 had ever spoken about the case and 
the content of those discussions, defense counsel talked the 
court out of this approach.  He argued that if Gonzalez were 
called, Peterson would be entitled to cross-examine Gonzalez 
more broadly, and thus the court could not call Gonzalez and 
agree to limit any questioning.  Instead, counsel proposed that 
the court bring in each juror for questioning, the precise 
approach the court adopted.  Peterson’s argument that the 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
99 
 
evidentiary hearing was unduly limited because Gonzalez was 
not called is forfeited.  (E.g., People v. Huggins (2006) 38 Cal.4th 
175, 238.) 
The contention is also without merit.  The court heard 
from every juror and alternate, each of whom denied discussion 
or prejudgment of the penalty phase verdict had occurred.  The 
court could credit that testimony.  It had before it a 
representation from Gonzalez’s counsel that Gonzalez would 
deny ever having discussed the case with Juror No. 8 and would 
otherwise invoke the Fifth Amendment, a representation that 
defense counsel expressly agreed was surely true.  In these 
circumstances, there was no abuse of discretion in failing to 
require Gonzalez to go through putting these statements on the 
record. 
H. Penalty Phase Issues 
Peterson raises procedural and evidentiary challenges to 
the conduct of the penalty phase trial and contends California’s 
death penalty scheme is unconstitutional.  Because we reverse 
the penalty verdict based on errors in jury selection, we need not 
address these claims.  (See People v. Armstrong, supra, 6 Cal.5th 
at p. 800.) 
 
 
PEOPLE v. PETERSON 
Opinion of the Court by Kruger, J. 
 
100 
 
III.  DISPOSITION 
We affirm the judgment as to guilt, reverse the judgment 
as to the sentence of death, and remand the matter for a new 
penalty determination. 
 
 
 
 
 
 
 
 
     KRUGER, J. 
 
We Concur: 
CANTIL-SAKAUYE, C. J. 
CHIN, J. 
CORRIGAN, J. 
LIU, J. 
CUÉLLAR, J. 
GROBAN, J. 
 
 
See next page for addresses and telephone numbers for counsel who argued in Supreme Court. 
 
Name of Opinion People v. Peterson   
__________________________________________________________________________________ 
 
Unpublished Opinion 
Original Appeal XXX 
Original Proceeding  
Review Granted     
Rehearing Granted 
 
__________________________________________________________________________________ 
 
Opinion No. S132449 
Date Filed:  August 24, 2020  
__________________________________________________________________________________ 
 
Court:  Superior    
County:  San Mateo    
Judge:  Alfred Delucchi    
 
__________________________________________________________________________________ 
 
Counsel: 
 
Cliff Gardner, under appointment by the Supreme Court; Catherine White and Lazuli Whitt for Defendant 
and Appellant. 
 
Kamala D. Harris and Xavier Becerra, Attorneys General, Gerald A. Engler and Ronald S. Matthias, 
Assistant Attorneys General, Glenn R. Pruden and Donna M. Provenzano, Deputy Attorneys General, for 
Plaintiff and Respondent. 
 
 
 
 
 
 
 
Counsel who argued in Supreme Court (not intended for publication with opinion): 
 
Cliff Gardner 
Law Office of Cliff Gardner 
1448 San Pablo Avenue 
Berkeley, CA 94702 
(510) 524-1093 
 
Donna M. Provenzano 
Deputy Attorney General 
455 Golden Gate Avenue, Suite 11000 
San Francisco, CA 94102-7004 
(415) 703-1303