How Paid Experts Help Exonerate Police After Deaths in Custody
"Inside the self-reinforcing ecosystem of people who advise, train and defend officers. Many accuse them of slanting science and perpetuating aggressive tactics.
An officer fired a Taser at Kevin Piskura’s chest for 11 seconds. He went into cardiac arrest and later died. A consultant working for Taser wrote:
The family sued, and the case settled out of court.
Officers in Phoenix held Miguel Ruiz in a neck hold. Asked in court about the possible dangers of this type of restraint, a doctor testifying as an expert witness for the city said:
A jury found in favor of the officers.
In 2019, deputies shocked Kevin Niedzialek twice with a stun gun and pushed him facedown into the ground. After he died, a doctor hired by the county wrote:
The family sued, and the case is ongoing.
When lawyers were preparing to defend against a lawsuit over a death in police custody in Fresno, Calif., they knew whom to call.
Over the past two decades, Dr. Gary Vilke has established himself as a leading expert witness by repeatedly asserting that police techniques such as facedown restraints, stun gun shocks and some neck holds did not kill people.
Officers in Fresno had handcuffed 41-year-old Joseph Perez and, holding him facedown on the ground, put a spinal board from an ambulance on his back as he cried out for help. One officer sat on the board as they strapped him to it. The county medical examiner ruled his death, in May 2017, a homicide by asphyxiation.
Dr. Vilke, who was hired by the ambulance provider, charged $500 an hour and provided a different determination. He wrote in a report filed with the court this past July that Mr. Perez had died from methamphetamine use, heart disease and the exertion of his struggle against the restraints.
Dr. Vilke, an emergency medicine doctor in San Diego, is an integral part of a small but influential cadre of scientists, lawyers, physicians and other police experts whose research and testimony is almost always used to absolve officers of blame for deaths, according to a review of hundreds of research papers and more than 25,000 pages of court documents, as well as interviews with nearly three dozen people with knowledge of the deaths or the research.
Their views infuriate many prosecutors, plaintiff lawyers, medical experts and relatives of the dead, who accuse them of slanting science, ignoring inconvenient facts and dangerously emboldening police officers to act aggressively. One of the researchers has suggested that police officers involved in the deaths are often unfairly blamed — like parents of babies who die of sudden infant death syndrome.
The experts also intersect with law-enforcement-friendly companies that train police officers, write police policies and lend authority to studies rebutting concerns about police use of force.
Together they form what often amounts to a cottage industry of exoneration. The dozen or so individuals and companies have collected millions of dollars over the past decade, much of it in fees that are largely underwritten by taxpayers, who cover the costs of police training and policies and the legal bills of accused officers.
Many of the experts also have ties to Axon, maker of the Taser: A lawyer for the company, for example, was an early sponsor of the Institute for the Prevention of In-Custody Deaths, a commercial undertaking that is among the police-friendly entities, and some of the experts have worked as consultants for Axon; another has served on Axon’s corporate board.
The New York Times identified more than 100 instances of in-custody deaths or life-threatening injuries from the past 15 years in which experts in the network were hired to defend the police. The cases were nearly all civil lawsuits, as the officers involved were rarely charged with crimes. About two-thirds of the cases were settled out of court; of the 28 decided by judges or juries, 16 had outcomes favoring the police. (A handful of cases are pending.)
Beyond the courtroom, the individuals and businesses have offered instruction to thousands of police officers and medical examiners, whose cause-of-death rulings often help determine legal culpability. Lexipol, a Texas-based business whose webinars and publications have included experts from the network, boasts that it helped write policy manuals for 6,300 police departments, sometimes suggesting standards for officers’ conduct that reduce legal liability. A company spokeswoman said it did not rely on the researchers in making its policies.
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The self-reinforcing ecosystem underscores the difficulty of obtaining an impartial accounting of deaths in police custody, particularly in cases involving a struggle, where the cause of death is not immediately clear. The Times reported earlier this year that outside criminal investigations of such cases can be plagued with shortcuts and biases that favor the police, and that medical examiners sometimes tie the deaths to a biological trait that would rarely be deemed fatal in other circumstances.
Some researchers and doctors in this ecosystem who responded to questions from The Times said they did not assist law enforcement but provided unbiased results of scientific research and opinions based on the facts of each case. Several pointed to research demonstrating that police struggles overall have an exceedingly low risk of death. They also highlighted health issues that could cause deaths in such circumstances, including drug use, obesity, psychological disturbances and genetic mutations that may predispose people to heart problems.
Some also criticized research and medical opinions that found that police techniques might cause or contribute to deaths, suggesting these were flawed. They also pointed out that other academic papers have been written by people who testify against law enforcement in such cases.
“Sensationalism, without offering scientifically demonstrated better control techniques, adds no benefit, and merely exacerbates the existing tensions between law enforcement and the society at large,” said Mark Kroll, a biomedical engineer who has backed the idea of an “arrest related death syndrome” as an explanation of the deaths.
Others in the network, including Dr. Vilke, said it was wrong to characterize their work as favoring the police, and suggested The Times’s analysis misrepresented it. “I would disagree,” Dr. Vilke said when The Times shared its findings with him. Another of the experts, Dr. Steven Karch, sent papers suggesting Black males and people exerting themselves were generally more likely to have sudden cardiac death.
Lawyers for Derek Chauvin, the former Minneapolis police officer who was ultimately convicted in last year’s murder of George Floyd, also drew upon the same network of researchers and experts. In particular, they turned to the defense of prone restraint, a technique in which officers subdue subjects facedown, as happened to Mr. Floyd. The work of Dr. Kroll, who has a Ph.D in electrical engineering but no medical degree, was cited by the Chauvin defense as proof that putting body weight on someone facedown does not cause asphyxia.
The experts have been called on to defend a broad range of other police techniques, including Taser shocks and neck holds. Medical examiners and investigators have also relied on the research:
Omaha police officers used a Taser 12 times when detaining Zachary Bear Heels in 2017 and punched him repeatedly in the head and neck. Dr. Kroll, who sits on Axon’s corporate board, testified in the criminal trial that the stun gun could not have contributed to the death of Mr. Bear Heels, a 28-year-old with bipolar disorder and schizophrenia. He also wrote a report in the civil case that is under seal.
Officers in Phoenix held Miguel Ruiz in a neck hold and shocked him multiple times with a stun gun in 2013. In a civil case, Dr. Vilke attested to the safety of neck holds that cut off blood flow to the head by compressing arteries, and another researcher, Dr. Charles Wetli, discussed excited delirium, a condition that some doctors say can suddenly kill drug users or the mentally ill.
Sheriff’s deputies in Kern County, Calif., handcuffed David Silva in 2013, bloodied him with batons, tied his hands and feet together behind his back, and pushed him facedown into the ground. Two physicians in the expert network, Dr. Karch and Dr. Theodore Chan, agreed with the coroner’s finding that Mr. Silva did not asphyxiate; Dr. Chan cited studies he had done on the subject.
Dr. Chan, who works in San Diego with Dr. Vilke, is also serving as an expert witness in the lawsuit over the death of Mr. Perez in Fresno. Citing his own research, he stated that there was “no evidence” that such weight on a person’s back could contribute to asphyxiation.
According to court documents, Mr. Perez had recently taken methamphetamines when police saw him behaving erratically. They handcuffed and tried to calm him, at one point putting a towel under him to keep him from injuring his face.
After an ambulance arrived, they placed a backboard on top of him and an officer sat on it. In a deposition, the officer said he had been trained that doing so posed no danger of asphyxia. A captain from the department said in the case that the training had relied on an article by Dr. Kroll.
“The problem is that when officers get sued in these cases,” said Neil Gehlawat, the lawyer for Mr. Perez’s family, the cadre of researchers insist that “‘no one can die this way,’ and then officers start to believe it.”
Mr. Perez’s sister, Michelle Perez, said that watching the video of his death was “terrifying” and that she didn’t understand why officers would push him facedown and sit on him.
“I just kept thinking, ‘Get off of him!’” she said. “There could have been some kind of different tactic.”
Testimony by Dr. Gary Vilke in the Joseph Perez case. Taylor & Ring
Shaping the Science
The physicians, scientists and researchers who come to the defense of law enforcement officers often cite experiments conducted on volunteers. They shock them with Tasers, douse them with pepper spray or restrain them facedown on the ground.
Their published findings are usually the same: that there is no evidence that the actions have enough of an effect to cause death.
A Times analysis of more than 230 scientific papers in the National Library of Medicine database published since the 1980s showed those conclusions to be significantly different from those published by others, including studies about restraints, body position and excited delirium.
Nearly three-quarters of the studies that included at least one author in the network supported the idea that restraint techniques were safe or that the deaths of people who had been restrained were caused by health problems. Only about a quarter of the studies that did not involve anyone from the network backed that conclusion. More commonly, the other studies said some restraint techniques increased the risk of death, if only by a small amount.
The few studies by the group that found problems with police techniques focused on deaths in which Tasers ignited gas fumes or caused people to fall and hit their heads.
Dr. Vilke’s first report on police restraint was funded by a $33,900 grant from San Diego County during a lawsuit over the 1994 death of Daniel Price. A woman reported seeing odd behavior from Mr. Price, 37, who had taken methamphetamines; officers restrained him facedown, his hands and feet tied together.
As part of their research, Dr. Vilke and others hogtied healthy volunteers. They observed that measurements of their lung functions decreased by up to 23 percent, which they concluded was not clinically significant because similar levels of diminished lung capacity could still be considered normal. The judge in the Price case cited the research when he dismissed the lawsuit.
The study and others have been challenged by some scholars and physicians because they are based on controlled conditions that are unlike real life, said Justin Feldman, a social epidemiologist at Harvard University who studies patterns of deaths in law enforcement custody.
“There’s a fundamental problem in terms of study design,” he said. “They’re not using people with more severe mental and physical disabilities. They’re not doing it with people who have taken drugs. When they’re testing Tasers, they aren’t using them as many times as you might see in some deaths.”
When their studies appeared in peer-reviewed publications, the network of experts acknowledged that their work had limitations. But when discussing the research in court, or during trainings and elsewhere, some of them used more expansive language, did not mention conflicting work, or said they had fully refuted scholars who disagreed.
In the Fresno lawsuit and others, for example, Dr. Chan repeatedly wrote that Dr. Donald Reay, a former medical examiner in King County, Wash., had concluded that hogtying “does not produce any serious or life-threatening respiratory effects” — omitting the crucial phrase “in normal individuals.” Other physicians in the network consistently left off that phrase when repeating the quote, although Dr. Reay maintained that such restraints could be fatal in some instances.
Dr. Chan did not respond to a question about the quotation.
Papers by researchers outside the network were more frequently balanced — finding, for example, that some restraint positions are generally safe while others can cause statistically significant changes in breathing. Another recent paper used new computer imaging technology to measure lung function and found that it was affected during restraint.
In their own writings and when asked about these papers, some scientists in the network dismissed them. They said papers that found “statistically significant” effects were inadequate because the changes were not “clinically significant” enough to be considered health problems in the participants. (Some other scientists said choosing test subjects who would be more likely to face such distress would generally not be ethically permitted in experiments.) They said some experiments with Tasers on animals could not be used to draw conclusions about humans. And several suggested that some of the other papers should be scrutinized because they were written by doctors who testified against police.
Dr. Kroll said in a 2019 webinar that “the science has completely debunked” the claim that pushing someone facedown could contribute to asphyxiation. In the session, conducted by Lexipol and titled “Arrest Related Deaths: Managing Your Medical Examiner,” he suggested that such deaths were outside the control of officers.
“Decades ago we used to prosecute mothers for crib deaths and sudden infant death syndrome, and then we figured out it really wasn’t their fault,” he said at one point in the training session, adding later: “Hopefully in the future we’ll have something like sudden infant death syndrome, just ‘arrest related death syndrome’ so we don’t have to automatically blame the police officer.”
A spokeswoman for Lexipol, which was co-founded by a lawyer who had previously hired Dr. Chan to defend police officers, said an upcoming webinar would discuss recent court rulings that found extended prone restraint to be excessive force in some circumstances.
“We are not in the business of determining such science-based decisions” about whether prone restraint is dangerous, the spokeswoman, Shannon Pieper, said in an email.
Some of the scientists are fierce defenders of their approach, vigorously challenging anyone who suggests an alternative finding. They submit letters to the editors of medical journals that publish the opposing research, discredit it in textbooks they write and routinely dismiss it as “junk science” in public forums.
One cardiologist, Dr. Peyman Azadani, said in an interview that he was intimidated by the pushback. In a 2011 academic paper, he reviewed studies by authors associated with Taser and found they were far more likely than others to conclude that the devices were safe.
Dr. Azadani said two people who identified themselves as being affiliated with Taser had approached him about the research during a medical conference.
“They knew everything about my background, and they told me I was destroying my future,” he recalled.
Having recently immigrated from Iran at the time, Dr. Azadani was concerned about making waves, he said, so he removed his name from subsequent papers and then changed research subjects.
In a statement, Axon said it had no information about the incident but did not condone such behavior. The company said it promoted research into its devices out of a concern for safety, and Dr. Kroll, who makes more than $300,000 a year as a member of Axon’s corporate board, pointed to a more recent study that found no correlation between Taser funding and safety determination.
A Network Forms
Dr. Wetli, a former Miami medical examiner who died last year, was among the first to publish research that launched what has become an industry of sorts defending police officers. He wrote in the 1980s about men who had taken cocaine and died, many while being subdued by the police. He attributed the deaths to a condition he called excited delirium, when someone becomes aggressive from a mental illness or psychoactive drugs.
Later, in 1994, two former law enforcement officers, Michael A. Brave and John G. Peters Jr., described in a paper what they called custody death syndrome. The condition, they wrote, had “no apparent detectable anatomical cause” but could be associated with excited delirium or other vague diagnoses.
In describing the death of a hypothetical suspect, they focused on potential liability: “You immediately cringe at the thought of the critical scrutiny you will soon be facing by the media, by council officials and by special interest groups,” they wrote.
The two men later became affiliated with both the Institute for the Prevention of In-Custody Deaths and Americans for Effective Law Enforcement, another group that provides legal resources for officers. Mr. Brave also became a lawyer for Taser.
In the early 2000s, as Tasers were adopted more widely, studies about them proliferated. A group of researchers led by Dr. Jeffrey Ho in Minneapolis pioneered the work. In their initial study, funded in part by Taser, they shocked volunteers for five seconds and concluded that measurements of heart health did not change.
For years, Dr. Ho has worked in emergency medicine at Hennepin Healthcare, as a part-time sheriff’s deputy and, until 2019, as the medical director for Axon.
Taser was also present at the creation of the Institute for the Prevention of In-Custody Deaths, which was founded in 2005 by Mr. Peters.
In an interview, Mr. Peters said he started the business because so many deaths were being blamed on Tasers, which he characterized as one of many misguided criticisms of police conduct. The institute conducts research and training that often rebuts the criticism and is one of several commercial forums that draw like-minded researchers about law enforcement behavior.
“When we first started teaching this stuff back in the ’90s, it was all pepper spray deaths,” he said. “Well, then they did the science and showed that of all the people who died, only two may have been associated with pepper spray. So that issue went away. Then positional asphyxia popped up. So we did a little bit of work in that area and then that quieted down.”
Taser provided some early funding to the institute in exchange for training programs, Mr. Peters said, and one of its initial sponsors was Mr. Brave, who joined Taser’s legal department around the same time.
“We put him on the board the first year so we would have a connection to information at Taser,” Mr. Peters said.
The institute had also worked closely with Deborah C. Mash, a neuroscientist who has written papers about excited delirium. When Dr. Mash was affiliated with the University of Miami, Mr. Peters and Taser representatives recommended that medical examiners send brain tissue samples from people who had died in police custody to her lab for testing. The Times found a handful of instances in which medical examiners relied on these test results to determine that someone had died of excited delirium as well as one case in which the results were used to rule it out.
Dr. Mash left the university in 2018. In an email to The Times, she said she tells officers that excited delirium is a medical emergency and that the proper response is to immediately request emergency medical help.
Another private company that lends expert support for the police, the Force Science Institute, has promoted research and commentary by Dr. Kroll, including a paper he wrote with Mr. Brave and Dr. Karch that tested law enforcement officers pressing their knees into a prone person’s back. They said their results did not support the theory that this could cause asphyxia.
The business of supporting law enforcement can be lucrative. Not all of the researchers testify frequently in court, but when they do, experts associated with the network typically earn $500 to $1,000 an hour for testimony and depositions. Lexipol charges thousands of dollars to review and write policies for police departments. The Institute for the Prevention of In-Custody Deaths also charges for its training programs and promotes its business partners.
At the institute’s annual conference in Las Vegas last month, law enforcement officers, lawyers and physicians attended presentations, some by experts in the network, on such topics as ways to subdue or restrain a suspect, and how to manage publicity when someone is injured or dies in custody. The price of admission: $695.
One-Sided Track Record
The Times found that, with rare exceptions, when members of this network weigh in on a case in court, they side with the police.
In court documents and testimony, some of them have acknowledged their one-sided track record.
“That’s like trying to retain Columbus to testify that the Earth is flat,” Dr. Tom Neuman, a retired emergency medicine physician in San Diego, said in 2018 when asked if relatives of people who had died in police custody would ever hire him as an expert.
In a deposition this past summer, Dr. Vilke said it had been 20 years since he had last testified that an officer was likely to have contributed to a death. In an email to The Times, he said that he had “no independent recall” about specific earlier work, and “would disagree” that his work over the past 20 years almost always found that law enforcement was not to blame.
Mr. Peters, who founded the training institute, is an exception. He has testified regularly on behalf of people harmed in police encounters, or their families, but his testimony has been limited to whether police procedures were followed. After Mr. Floyd was killed in Minneapolis, Mr. Peters released a video statement saying that putting a knee on a someone’s neck should not be permitted under any use-of-force policy.
Making determinations on death-in-custody cases is a complex and inexact process. The people being detained in the instances reviewed by The Times were often on drugs or in psychological distress, and some had severe medical conditions.
But in death after death, The Times found, actions by law enforcement officers fell well outside the controlled conditions in the research the experts cited to exonerate them. Occasionally, the experts used identical language in different cases to rebut allegations and suggest alternative explanations for the deaths. They also emphasized common ailments like heart disease, or leaned heavily on the poorly understood notion of excited delirium.
(differences highlighted) It should be noted that in the video that after being handcuffed on laying on the ground, Mr. Barrera could be heard stating, “I can’t breathe” shortly after he asked for some water. At face value, one might think this evidence that Mr. Barrera could not breathe or ventilate. However, when evaluating the video, Mr. Barrera was clearly moving air in and out of his lungs very well, talking loudly, and had no clinical evidence of ventilatory restriction at the time he was saying this. What was likely happening is that Mr. Barrera was having a cardiac event not a pulmonary event.
In 2010, officers in Palm Desert, Calif., responding to a 911 call found 48-year-old Robert Appel delusional. Multiple officers pinned him facedown with their knees. When they turned him over after what the officers described as a short time, he was dead. Dr. Vilke blamed cardiac arrest caused by undiagnosed kidney failure.
Mathew Ajibade hit his girlfriend in January 2015 while experiencing what his family described as a manic bipolar episode. Deputies in Savannah, Ga., beat him, handcuffed him, put him in a restraint chair with a spit mask over his face and shocked him four times in the groin with a Taser.
Dr. Mash and Dr. Wetli both reported that the actions had not led to Mr. Ajibade’s death. Dr. Mash blamed natural causes associated with his bipolar disorder and said he exhibited signs of excited delirium, while Dr. Wetli said it was related to sickle cell trait, a typically benign condition in which a person carries one of the two genes that together cause sickle cell disease.
Assessing the effectiveness of the opinions exonerating the police is difficult because most cases settle or are decided without explanation.
But several cases reviewed by The Times suggest that the research has had far-reaching effects — influencing investigator decisions in death inquests and giving officers assurance that their methods are safe. Some of the experts’ legal statements and educational materials they have prepared for police called safety warnings by Taser and other law enforcement groups outdated or needlessly conservative.
In a deposition in April, the sheriff in Riverside County, Calif., cited studies backed by the law-enforcement-leaning experts to explain why his deputies held people facedown after handcuffing them. The sheriff, Chad Bianco, described the position as “the absolute safest place for any subject.”
Two years ago, deputies working for Sheriff Bianco found Kevin Niedzialek, 34, bleeding from a head wound and behaving strangely after taking methamphetamines. They shocked him twice with a Taser, and held him facedown.
When they rolled him onto his back, Mr. Niedzialek was unresponsive. He died the next day."
Produced by Eden Weingart