When they carried the body of a 32-year-old Black man named Lamont Perry out of the woods in Wadesboro, N.C., there were no protests over his sudden death in police custody.

No reporters camped at the scene. No lawyers filed suit.

Instead, the final mark in the ledger of Mr. Perry’s life was made by a state medical examiner who attributed his death in large part to sickle cell trait, a genetic characteristic that overwhelmingly occurs in Black people. The official word was that he had died by accident.

But the examiner’s determination belied certain facts about that night in October 2016, public records and interviews show. Accused of violating probation in a misdemeanor assault case, Mr. Perry was chased by parole and local police officers through the dark into a stand of trees, where only they could witness what happened next.

He had swelling of the brain, and a forensic investigator reported that he had an open fracture of his right leg. He was covered in dirt, and residents of a nearby housing complex told his family that when the officers emerged from the woods, their shoes and the bottoms of their pants were spattered in blood.

Mr. Perry’s case underscores how willing some American pathologists have been to rule in-custody deaths of Black people accidents or natural occurrences caused by sickle cell trait, which is carried by one in 13 Black Americans and is almost always benign. Those with the trait have only one of the two genes required for full-blown sickle cell disease, a painful and sometimes life-threatening condition that can deform red blood cells into crescent shapes that stick together and block blood flow.

As recently as August, lawyers for Derek Chauvin, the Minneapolis police officer convicted last month of murdering George Floyd, invoked sickle cell trait in an unsuccessful motion to dismiss the case against him, saying that the condition, along with other health problems and drug use, was the reason Mr. Floyd had died.

The New York Times has found at least 46 other instances over the past 25 years in which medical examiners, law enforcement officials or defenders of accused officers pointed to the trait as a cause or major factor in deaths of Black people in custody. Fifteen such deaths have occurred since 2015.

In roughly two-thirds of the cases, the person who died had been forcefully restrained by the authorities, pepper-sprayed or shocked with stun guns. Scattered across 22 states and Puerto Rico, in big cities and small towns, the determinations on sickle cell trait often created enough doubt for officers to avert criminal or civil penalties, The Times found.

K.C. Cage-Singleton, a 30-year-old landscaper and father of four, was walking in Baton Rouge, La., in October 2009 when two officers approached him because they thought his clothing resembled that of an armed robbery suspect. Records show they chased him into an apartment complex, shocked him with a stun gun and beat him with a baton. The coroner cataloged a slew of injuries, including abrasions, lacerations and broken teeth, but said the manner and cause of his death were “undetermined,” citing “probable” sickle cell trait. The officers were not charged.

Army Sgt. James Brown, 26, had completed two tours in Iraq and was struggling with post-traumatic stress disorder in July 2012 when he turned himself in to the El Paso jail to serve a two-day sentence for drunken driving. The authorities said he became violent, and he died after five jailers in riot gear piled atop him, pulled a mesh mask over his head and bound him in a chair. The medical examiner ruled that he had died a natural death caused by sickle cell crisis, and a grand jury declined to bring charges.

Gamel Brown, a 30-year-old property maintenance supervisor, cut his hand on a broken mirror at his home in a Baltimore suburb in January last year, prompting a call to 911. The police who responded said he became “extremely combative,” and they jolted him several times with a stun gun. After he died at a hospital, the medical examiner said that the manner of his death was undetermined — and that it was caused in part by sickle cell trait. The state’s attorney filed no charges.

In three cases, deaths linked to sickle cell trait that were deemed natural or of indeterminate cause were later ruled homicides — as occurred when Martin Lee Anderson, 14, died at the hands of his jailers at a northwest Florida juvenile detention camp in January 2006.

“You can’t put the blame on sickle cell trait when there is a knee on the neck or when there is a chokehold or the person is hogtied,” said Dr. Roger A. Mitchell Jr., the former chief medical examiner for the District of Columbia and now chairman of pathology at the Howard University College of Medicine. “You can’t say, ‘Well, he’s fragile.’ No, that becomes a homicide.”

Not every death that is tied to the condition is inherently questionable. Medical experts say sickle cell trait has caused deaths in rare cases of extreme overexertion, especially among military trainees and college athletes. Three of the in-custody deaths identified by The Times involved people who were exercising vigorously in jail yards or running hard before they collapsed — and law enforcement officers said that at most they put handcuffs on them.

In none of the deaths examined by The Times did the person have actual sickle cell disease, though there were instances when imprecise language by medical examiners left the false impression the trait and the disease were the same.

Dr. James R. Gill, chief medical examiner in Connecticut and president of the National Association of Medical Examiners, said that pathologists would not be doing a thorough job if they identified sickle cell trait and failed to mention it in their reports.

“We know that this, in the right situation, can cause death, and you can’t just ignore that,” said Dr. Gill, who cited the trait in the autopsy of Lashano Gilbert, a 31-year-old Black man who had died in police custody in October 2014.

Mr. Gilbert, who had attended medical school, suffered a psychotic episode in New London, Conn., and was arrested after jumping on a passing car. His jailers put him in restraints, used pepper spray and a stun gun on him and fit him with a mask to prevent biting. Dr. Gill ruled the death a homicide, though the state’s attorney deemed the use of force “appropriate” and filed no charges.

In interviews, Dr. Mitchell and other medical experts agreed that the trait warranted mention in autopsies, but said any natural or accidental death attributed to it, even in part, should be scrutinized if the person died during or after a struggle with law enforcement.

Many said they suspected some sickle cell determinations might reflect a pattern of bias or conflicts of interest among medical examiners and police officials.

Forensic pathologists, the doctors who conduct autopsies for coroners and medical examiners, were singled out in a hotly disputed study published in a scientific journal in February suggesting that racial bias could influence their rulings, though it did not address sickle cell trait.

And coroners and medical examiners have entrenched relationships with law enforcement in many areas, functioning as part of police departments or working closely with them. In California, for example, the elected sheriff serves as coroner in 41 of the state’s 58 counties. Several years ago, two pathologists resigned from the coroner’s office in San Joaquin County there, citing interference by the sheriff with in-custody death reviews. The sheriff denied the claims and lost re-election.

In Mr. Perry’s case, agents with the North Carolina State Bureau of Investigation sealed his body in a bag before a forensic investigator inspected it. Officers at the scene could not say for sure how he had suffered his injuries, but said it appeared he had tripped and fallen into a ravine. The officers said he had been talkative when they found and handcuffed him, but then he lost consciousness. No efforts were made to revive him with lifesaving equipment when paramedics arrived, records and interviews show, and the “open fracture” documented by the forensic investigator was described in the autopsy as a “laceration.”

Mr. Perry, who was sometimes shy to the point of seeming rude, had his detractors in the neighborhood, his family members said, and records show he had a history of misdemeanor breaking-and-entering, larceny and drunken-driving convictions. The assault conviction that gave rise to the foot chase stemmed from an argument with the girlfriend he was visiting that night, family members said.

Mr. Perry had alcohol and a small amount of cocaine in his bloodstream when he died, and the medical examiner ruled that he had succumbed to “cocaine toxicity in the setting of sickle cell trait,” effectively ending any deeper inquiry. The local district attorney declined to bring charges.

“I find no evidence of any criminal activity or wrongdoing of any kind,” the district attorney, Reece Saunders, wrote in March 2017. “I consider this unfortunate matter closed.”

For Mr. Perry’s relatives, who could not afford a lawyer to challenge the ruling, all that was left was a series of unanswered questions. What had happened in the woods? Why wouldn’t the investigators let them view the body before the autopsy?

“The only people who know what happened are that probation officer and the officers who ran out there,” said Mr. Perry’s half brother, Mario Robinson. “I don’t believe what they said.”

A Nationwide Pattern

To gain a sense of how often medical examiners have used sickle cell trait to explain in-custody deaths, The Times reviewed thousands of pages of autopsy records, court filings and police reports. It examined data on suspicious deaths from more than 30 of the United States’ largest counties, whose jurisdictions cover nearly one in three Black Americans.

The review identified dozens of cases dating to the 1970s and was almost certainly an undercount. In some areas with large Black populations, like New York City, The Times relied on court cases and media reports because relevant medical or identifying data was not publicly available. Other locations, including Wayne County, Mich., which contains Detroit, did not provide the data to The Times before publication.

Many of the deaths received little outside scrutiny at the time — perhaps a brief mention in the local media — in part because the families did not have the resources to challenge official determinations, or because the detained people were not seen as particularly sympathetic. Many had histories of arrests on drug use, domestic violence or other charges, and additional evidence that might point to police misconduct, such as video footage, was often not made public.

In some cases, The Times only pieced together details of the deaths through interviews with relatives, witnesses, emergency workers and outside pathologists.

The results offer a vivid glimpse into deaths in custody. In the past 25 years, 19 cases involved Black people who died after being restrained in ways that could hinder breathing. Twelve deaths occurred after the police or sheriffs’ deputies used stun guns. Nine happened after they used pepper spray. Two followed bites from police dogs.

Five of the cases were initially ruled homicides.

The rest were labeled undetermined, accidental or natural.

In communities from California to Pennsylvania, officials cited the rulings in closing investigations into the deaths, ensuring that police agencies provided the last word on what had occurred.

David Campbell, 25, stopped breathing in Allentown, Pa., in October 2011 after resisting his jailers’ efforts to remove his clothing and put him on suicide watch. They responded by dousing him with pepper spray, jamming knees into his back and leaving him tied to a chair, according to a lawsuit brought by his family.

While the results of Mr. Campbell’s autopsy were pending, emails show, the head of the Lehigh County Corrections Department sent the coroner a video of the arrest of a Florida man whose death was attributed to “excited delirium” — a condition that pathologists say can suddenly kill drug users or the mentally ill, though they acknowledge it is poorly understood and unevenly applied.

“I found this video which appeared similar to our incident with David Campbell,” wrote the corrections chief, Edward Sweeney, “and I thought I’d share it with you as we await the toxicology report.”

The coroner’s ruling in the case stated: “excited delirium complicating sickle cell trait, dehydration and abnormalities of the cardiac conduction system during restraint.” Manner of death: “undetermined.”

Ronney Moss Jr., wanted on suspicion of smoking marijuana outside a Greyhound bus station in Atlanta, suddenly was unable to breathe in August 2012 in the presence of an Atlanta police officer after running less than two-tenths of a mile. Investigators told the Fulton County medical examiner that the officer had not restrained Mr. Moss but instead found him on the ground gasping for air. The medical examiner attributed the death of Mr. Moss, 31 and apparently in good physical condition, to natural causes, particularly sickle cell trait “following exertion.”

Jason Pierce, 40, had been held for days in July 2017 at Louisiana’s Orleans Parish jail — where two guards would later be charged with smuggling drugs and other contraband — when he died in with cocaine and opiates in his system. After Mr. Pierce’s autopsy, the coroner’s office focused not on the drugs but on sickle cell trait, ruling that he had died a natural death caused by “widespread red blood cell sickling.”

A handcuffed Dean Smith, 25, told the police that he could not breathe following a foot chase in Evansville, Ind., in February last year. An officer standing over him said, “Boy, you are being overly dramatic,” according to body camera footage. Mr. Smith’s death would be recorded by the Vanderburgh County coroner as an accident prompted by sickle cell crisis and cocaine and alcohol intoxication.

Three months later, Larry Ross Jr., 37, died after state police officers arrested him in Cambridge, Md. The officers said they handcuffed Mr. Ross, who had run from his car after they stopped him for a traffic violation, without handling him roughly. The county medical examiner determined that his death was an accident caused by synthetic marijuana use, with sickle cell trait as a factor.

The Times described its findings to Simon Dyson, a British researcher who studies sickle cell conditions and deaths in custody. He said the cases follow a well-established pattern in which the trait is listed alongside other conditions, like high blood pressure or drug use, to create doubt about the role of law enforcement.

“It’s all throwing a smoke screen up around the death that makes it more difficult to effect a prosecution,” he said.

Determining whether a death is a homicide is ultimately a judgment call, though most pathologists interviewed by The Times said they applied the label if the intentional actions of one person led to the death of another — even if those actions were taken by the police and the person who died had health problems.

But not all medical examiners agree on how much another person’s actions must contribute to the death to call it homicide. Dr. Lisa Scheinin, a former deputy medical examiner in Los Angeles, who wrote a journal article in 2009 about sickle cell trait, said she had been “very hesitant” to rule in-custody deaths homicides unless the police had played an important role.

“If you call something homicide, there’s going to be all kinds of people waiting to sue you, to sue law enforcement,” Dr. Scheinin said in an interview. “We generally have to make decisions without thinking about other consequences, but sometimes you just can’t help think about that.”

A Medical Debate

Most people with sickle cell trait never suffer a symptom, though studies and experts have suggested that on rare occasions it can cause the fatal curving of blood cells in people who overexert themselves when other conditions are present — for example, hot weather, high altitude or drug use.

Dr. Bruce Mitchell, the former director of hospital medicine at Emory University Hospital Midtown in Atlanta, who has studied sudden death and sickle cell trait, said the condition had been cited in the deaths of some military recruits because they are often made to run long distances in the heat and with heavy equipment without enough training or conditioning.

Several doctors and researchers who spoke with The Times said they would be skeptical of in-custody deaths attributed to sickle cell trait, unless the situation also involved other risk factors.

“The analogy I would make would be to someone who has heart disease,” Dr. Mitchell said. “It might be true that they died because of heart disease, but, well, they probably would have lived if you hadn’t put them in a chokehold and stressed their heart.”

In at least three cases reviewed by The Times, the person was exerting himself and did not appear to interact significantly with law enforcement. In another, the environment was harsh: Darryl Daniels, 30, stopped breathing in Reno, Nev., in 1998 after taking cocaine and running for several blocks in 97-degree weather. The pathologist acknowledged that sickle cell trait was “usually benign and asymptomatic except under circumstances of extreme stress,” but wrote that the heat, activity and stimulant drugs provided that stress even before the man was arrested.

More often, The Times found, the police reported that the arrested people struggled, prompting the medical examiner to rule that their physical activity precipitated a so-called sickling crisis, when the blood cells bend into crescents and block blood vessels. In many instances, law enforcement also used control techniques that doctors said could limit oxygen enough to cause sickling and death. These included repeatedly using stun guns and pepper spray and holding people facedown with their arms behind them.

Sickle cell trait alone cannot cause death, said Dr. Swee Lay Thein, a hematologist at the National Institutes of Health who has studied the condition. “It has to be something else, and something quite extreme,” she said.

Medical experts also said it could be misleading to attribute death to the trait based on the presence of cells that have clumped or sickled — something that often happens when people with the condition stop breathing. Finding the crescent-shaped blood cells during an autopsy is to be expected, the experts said, and does not mean the cells were like that before death.

In the case of Mr. Floyd, the medical examiner in Minneapolis noted the curved cells and said he had had sickle cell trait. But the autopsy indicated that it had not contributed to his death, and there was no evidence the cells had sickled before he died. In their unsuccessful motion to dismiss the case, Mr. Chauvin’s lawyers nonetheless suggested that the trait could cause trouble breathing.

The argument echoed claims made in other cases as early as 1973, The Times found. That year, 28-year-old George Lucas died in the Cook County jail in Illinois, according to media reports at the time. Inmates testified that guards had beaten, strangled and suffocated him with a blanket, while jail officials said they had only strapped him to his bed.

But after sickled cells were found during the autopsy, the coroner said Mr. Lucas would not have died were it not for the trait, Dr. James Bowman, a pathologist who participated in the hearing, wrote in an academic article years later. The death was deemed natural and the guards were not charged. “Thus,” Dr. Bowman wrote, “the dangerous precedent for legalized murder of persons with sickle cell trait could become established.”

Seeking Answers

For decades, coroners and medical examiners have reached for answers when pressed to explain deaths of people in police custody.

One of the most prominent proponents of citing sickle cell trait was Dr. Charles V. Wetli, a pathologist who originated the idea that in-custody deaths could be caused by excited delirium.

During that chapter of his career, as a deputy chief medical examiner in Miami in the 1980s, Dr. Wetli theorized that men who died after arrest had often succumbed to the syndrome. But it was not only men who were susceptible, Dr. Wetli told reporters in 1988. Excited delirium may also have felled nine Miami women who were found dead in sexual poses, he said, in situations that might lead others to conclude that they had been raped and murdered. Nearly all the women were Black.

“For some reason, the male of the species becomes psychotic, and the female of the species dies in relation to sex,” Dr. Wetli told The Miami News at the time. That came under serious doubt about six months later, when the police arrested a man on a rape charge who they believed was a serial killer responsible for the deaths, which numbered 32 in all. The man died in prison after being convicted of the rape.

Dr. Wetli, who died in July, moved to New York in 1995 and became the chief medical examiner in Suffolk County, where he oversaw identification of the remains of victims in the crash of Trans World Airlines Flight 800.

In his later years, he became an outspoken backer of using sickle cell trait to explain in-custody deaths of Black people, writing a journal article with Dr. Scheinin of Los Angeles and testifying as a $450-an-hour expert witness hired by police agencies. He also acted as a paid consultant for Taser International, the maker of the stun guns cited in some of the deaths reviewed by The Times.

In 2008, Baron Pikes, known as Scooter, died after being shocked with a stun gun at least eight times by a police officer in Winnfield, La., while handcuffed and lying on the ground. The coroner ruled the death of Mr. Pikes, 21 and Black, a homicide, and the officer, Scott Nugent, was charged with manslaughter. Still, at the criminal trial, Dr. Wetli testified that “the cause of death was exertional sickling due to sickle cell trait.”

Mr. Nugent was acquitted.

The Times found other medical examiners invoking the trait as early as the 1970s.

In May 1979, Los Angeles pathologists blamed “massive intravascular sickling” in the death of Jerry Eugene Wright Jr., a 20-year-old Black man whom police officers had mistaken for a drug user. In fact, he had been the victim of a violent robbery; they handcuffed him, put him facedown on the ground and ignored bystanders who warned that he was struggling to breathe. Mr. Wright’s family was later awarded $2.1 million after suing for wrongful death.

A panel convened by a coroner outside Augusta, Ga., concluded that Larry Gardner, 33, had died of cardiopulmonary arrest caused by sickle cell trait in August 1984 after the authorities arrested him on marijuana and shoplifting charges. Mr. Gardner’s death led to rioting after it was said that he had been beaten in custody.

Authorities in Burlington County, N.J., cited sickle cell trait in the cases of two brothers who had died in police custody 15 years apart. They used it first to explain the sudden death of Sidney Miles, 20, while he was fleeing officers who sought to arrest him on a charge of driving without a license in 1984.

They cited it again when his brother, Cleathern Miles, 28, stopped breathing in 1999 after the police shot him with pepper spray and restrained him in the midst of an apparent mental breakdown — during which he was calling out his dead brother’s name. The same pathologist, Dr. Dante Ragasa, conducted both autopsies.

“There were allegations of police brutality in Sidney’s death, but that was not the case,” the acting county prosecutor, James Gerrow, told reporters in 1999. “Sadly and tragically, this mirrors what happened to Sidney.”

“There was,” he added, “no police misconduct in either case.”

Cautionary Tales

The death of Martin Lee Anderson, the 14-year-old Florida boy, shows the potential pitfalls when medical examiners rush to blame sickle cell trait.

An autopsy deemed Martin’s death to be natural, saying the trait was why he had suddenly stopped breathing in January 2006. But a later inquiry found that he had died after drill instructors at a Bay County, Fla., juvenile detention center punched and kneed him, pinned him down, pressed their fingers into pressure points and covered his mouth while forcing him to inhale ammonia.

Seven guards and a nurse were charged with manslaughter. All were acquitted, but the state agreed to settle a lawsuit brought by the family for $5 million.

The case of Derek Williams, who died in Milwaukee in July 2011, offered another cautionary tale.

The police saw Mr. Williams, 22, on a street corner and arrested him on suspicion of robbery after chasing him into the yard of a nearby home. He stopped breathing in the back seat of a patrol car. The police told the county medical examiner that he had been taken into custody “without incident,” and the medical examiner, based solely on that account, ruled that he had died a natural death caused by sickle cell crisis.

After being confronted with information reported by The Milwaukee Journal Sentinel, which showed, among other things, that officers had piled onto Mr. Williams during his cuffing and did not immediately respond to his pleas as he gasped for air, the county reversed itself and declared his death a homicide. Still, none of the officers were charged. Mr. Williams’s family settled a lawsuit against the city for $2 million.

The urge to elevate sickle cell trait over other factors was evident in more recent cases, too, The Times found, including when the police arrested Darren Boykin in Texarkana, Texas, in 2019.

Mr. Boykin, 23, had grown up in Ohio and gotten in trouble there for using counterfeit money to buy a gaming system, records show. He pleaded guilty to a misdemeanor charge before moving to Texarkana to live with his mother.

In August 2019, a Texarkana College employee saw him walk into an administration building and became suspicious, thinking he resembled a suspect in burglaries on campus. She called the police, who chased Mr. Boykin for about a third of a mile before an officer tackled him from behind. Mr. Boykin struggled as the officer tried to handcuff him, records show, and another officer joined to subdue him.

Mr. Boykin began showing signs of distress on the way to the jail. Patrol car footage showed him lapsing in and out of consciousness, apparently without the officer in the car taking notice, records show. “Had the officer not been paying attention to driving,” the Texas Ranger who investigated the death would tell the medical examiner, “she probably would have transported him straight to the hospital.”

The authorities realized he had stopped breathing only after he had reached the jail. They started pumping on Mr. Boykin’s chest to try to revive him, according to the investigators, and brought him to a hospital, where a doctor determined he had died.

The medical examiner noted abrasions on Mr. Boykin’s shoulder and bruising on his back, the autopsy report shows, but ruled that he had died of complications of sickle cell trait, citing the short distance he had run and the hot weather.

The manner of his death: natural.

Andrew Chavez contributed reporting, and Kitty Bennett contributed research.