When Damien Cameron’s body arrived at the Mississippi State Medical Examiner’s Office in August 2021, it bore all the signs of a police brutality case.

Mr. Cameron’s face was bloody and swollen almost beyond recognition from his struggle with Rankin County sheriff’s deputies the week before.

Signs of internal bleeding in the neck of Mr. Cameron, a 29-year-old Black man, suggested a deputy might have pinned him to the ground with a knee — a dangerous restraint technique condemned by the Justice Department and banned in many cities.

But when the state’s chief medical examiner, Dr. Staci Turner, completed her autopsy, she ruled the cause of Mr. Cameron’s death “undetermined.” A grand jury later declined to indict the deputies involved.

Now, three renowned pathologists, who examined Mr. Cameron’s autopsy report at the request of The New York Times and Mississippi Today, say his death should have been ruled a homicide.

After independently reviewing autopsy photos, sheriff’s reports, hospital records, and eyewitness statements saying two deputies knelt on Mr. Cameron’s neck for 10 minutes or more, the experts concluded the deputies most likely killed him.

His death was “a homicide, absolutely,” said Dr. Michael Baden, a former New York City chief medical examiner who testified in the OJ Simpson trial and performed an independent autopsy of George Floyd. “This person died of asphyxia because of neck compression.”

“There’s really nothing to be undetermined about,” said Dr. Zhongxue Hua, chief of the forensic pathology division at Rutgers University.

The opinions of these forensic experts give new ammunition to Mr. Cameron’s family, who have struggled to bring attention to his death for more than two years. Despite local media coverage and two articles by the news site Insider, Mr. Cameron’s death never surfaced nationally like the cases of George Floyd or Eric Garner.

Mr. Cameron’s mother, Monica Lee, described her son as an outgoing young man who could quickly turn strangers into friends with his smile. Ms. Lee has always maintained that the deputies killed her son by violently subduing him and ignoring his cries that he could not breathe. She predicted the investigation into his death “was going to be a bunch of lies.”

Ms. Lee sued the department in 2022.

Her lawyer, Malik Shabazz, said the conclusions of the independent pathologists could change the outcome of Ms. Lee’s case. “There’s serious questions about the competency and the accuracy of the autopsy findings,” he said.

Mr. Cameron is one of at least nine men who have died during episodes involving Rankin deputies since 2014, according to department records and Mississippi Bureau of Investigation reports.

Rankin County, a rural, majority-white community outside Jackson, has been rocked by national controversy this year after five sheriff’s deputies and a local police officer broke into the home of two Black men, tortured them for two hours, sexually assaulted them with a sex toy and then shot one of them in the mouth. All of the officers have pleaded guilty to federal and state charges.

On Aug. 3, Deputy Hunter Elward admitted to sticking his gun in 32-year-old Michael Jenkins’s mouth and firing it. He and the other officers, who are all white, concealed their crimes by planting a gun and drugs on their victims, disposing of security camera footage and falsifying sheriff’s reports, according to an investigation by the Justice Department.

“Obviously these officers can’t be trusted,” said Sean Tindell, commissioner of the Mississippi Department of Public Safety. “There’s probably going to be a lot of reviews of every case that they’ve ever worked on.”

Mr. Elward was one of the two deputies accused of kneeling on Mr. Cameron the day he died.

A violent arrest

The only witnesses to Mr. Cameron’s arrest on July 26, 2021, were the deputies, Ms. Lee and her parents.

That afternoon, a neighbor called the police to report a burglary he believed Mr. Cameron had committed at his home in a quiet, rural neighborhood near Braxton, Miss., court records show.

When Deputy Elward arrived to investigate, Mr. Cameron, who had been diagnosed with bipolar disorder and schizophrenia, swung at him and ran away, according to the sheriff’s report.

Deputy Elward fired his Taser and tackled Mr. Cameron, he claimed in his sheriff’s report, punching him three times in the face before Deputy Luke Stickman arrived to help subdue and arrest the man.

Mr. Cameron continued to resist the deputies as they led him outside and shoved him in a patrol car, Deputy Elward contended in his report.

Shortly after, he found Mr. Cameron unresponsive. Paramedics took him to University of Mississippi Medical Center, where he was pronounced dead.

Mr. Cameron’s family said they witnessed a drastically different encounter.

In interviews with reporters, Ms. Lee said her son never tried to hit the deputy.

Hours after the incident, Mr. Cameron’s grandfather told Mississippi Bureau of Investigation agents that he had witnessed a deputy placing his knee on his grandson’s neck as he lay on the ground. The deputies did not mention kneeling on Mr. Cameron in their reports.

Ms. Lee told reporters that Deputies Elward and Stickman knelt on Mr. Cameron’s neck and back for at least 10 minutes.

“He was telling me he couldn’t breathe, he couldn’t breathe,” she said.

Mr. Cameron’s mother told reporters that he struggled to walk as the deputies took him to the patrol car and that he fell facedown in the mud in front of it

There is no video footage of the incident.

In a written statement, Sheriff Bryan Bailey said the department had yet to deploy body-worn cameras when Mr. Cameron was arrested. Mississippi does not require law enforcement agencies to use them.

Without footage to prove her claims, Ms. Lee hoped her son’s autopsy would finally reveal the truth about his death.

But after the medical examiner’s report came back “undetermined,” a grand jury declined to charge the deputies.

“It was heartbreaking,” Ms. Lee said. “This is what you do every day, and you could not determine his cause of death? Why?”

District Attorney John Bramlett, known as Bubba, who presented the case to the grand jury, did not return calls seeking comment about the case.

Medical examiners’ findings serve as the legal foundation for prosecutors to file charges against officers involved in fatal incidents, legal experts said.

“The only person in a homicide case who can testify to the ultimate issue — that the manner of death was homicide — is a medical examiner,” said Aramis Ayala, a former Florida state attorney and a professor at Florida A&M University School of Law.

Prosecutors rarely pursue homicide charges against police officers. Without an official cause of death, experts said the chances of persuading a grand jury to indict an officer were slim.

A death unexplained

Dr. Turner declined to discuss the details of Mr. Cameron’s autopsy, but said there was nothing unusual about her decision not to cite a cause of death.

In cases where her office is missing information or can’t definitively cite a cause, “we err on the side of ‘undetermined’ because we don’t want to make a mistake,” she said.

Dr. Turner would not comment on what police documents and witness statements she had access to when she performed the autopsy. But in her report she wrote, “Due to lack of access to information involving the circumstance of this death, the cause and manner of death are best classified as undetermined.”

All three independent forensic pathologists said the medical examiner should have tracked down the information she needed to make a determination. The hemorrhaging in Mr. Cameron’s neck made it clear he died of asphyxiation, they said.

“They should not have signed it on as undetermined and let it go,” said Dr. Cyril Wecht, former president of the American College of Legal Medicine and the American Academy of Forensic Science. “That was up to them to get more information from the cops.”

A toxicology report found methamphetamine in Mr. Cameron’s blood, but the pathologists agreed that the drug did not cause his death.

Representatives of the medical examiner’s office said the agency would review the case again if asked by the Mississippi attorney general or the local district attorney’s office.

“It was undetermined,” said Mr. Tindell, the public safety department commissioner. “That doesn’t mean it can’t be determined later.”

A representative of the attorney general’s office referred reporters to District Attorney Bramlett, who did not respond to requests for comment.

In a written response to The Times, Sheriff Bailey said his department cooperated with the Mississippi Bureau of Investigation’s inquiry, noting that the bureau found no wrongdoing.

“If requested, we will fully cooperate with any future investigation into this incident by any investigative agency,” Sheriff Bailey wrote.

Mr. Shabazz said he planned to consult with the pathologists and update Ms. Lee’s lawsuit to include their findings. He hopes the new information will prompt state officials to review the case again.

Ms. Lee said she just wanted the world to know the truth.

“This is what they did to my child,” she said. “You can’t tell me it was undetermined.”

Nate Rosenfield and Brian Howey are reporters for the Mississippi Center for Investigative Reporting at Mississippi Today, a non-profit newsroom covering the state.