Denver • The death of a 112-pound jail inmate who choked on his own vomit and suffocated after Denver sheriff's deputies restrained him during a psychotic episode is drawing new attention to the way he was subdued: facedown on his stomach with five deputies holding him to the floor.
Experts warn the common but risky police tactic of restraining someone in a prone position can be lethal, especially for those with medical problems and the mentally ill, whose distress is sometimes confused with resistance.
While the method has been linked to several deaths nationwide, some in law enforcement say it remains one of the most effective ways to stay safe while controlling a combative person.
Denver officials on Friday released surveillance footage of deputies' encounter with Michael Marshall, 50, a homeless man who had been jailed for trespassing and died because of "complications of positional asphyxia," according to the medical examiner.
District Attorney Mitch Morrissey said he wouldn't file criminal charges against the six deputies involved, saying multiple factors, including lung and heart disease, also contributed to his death. The deputies' use of force was necessary against the struggling inmate, Morrissey said.
"He didn't try to hurt anyone. He wasn't threatening," his niece, Natalia Marshall, said. "And for them to forcefully restrain him the way they did and brutally murder him just because of the fact that he was trespassing? Is beyond my thoughts."
The case, which prompted calls for a federal investigation, recalled the similar death of Marvin Booker, a homeless street preacher in 2010 after Denver deputies shocked him with a Taser while he was handcuffed, put him in a sleeper hold and lay on top of him.
The medical examiner said he died of "cardio-respiratory arrest during restraint."
The Justice Department has long warned officers about the dangers of "positional asphyxia," or death because someone's position complicates their ability to breathe. "As soon as a suspect is handcuffed, get him off his stomach," the DOJ wrote in a 1995 bulletin.
Problems arise when a person is held prone for prolonged periods, experts said.
No agency collects data showing how many people nationally suffocate as a result of being restrained facedown, so it's impossible to say whether use of the tactic has increased.
But the technique has been cited in several high-profile deaths, including that of Robert Ethan Saylor, an overweight man with Down syndrome who died after a struggle with deputies in a Maryland movie theater; Tanisha Anderson, a mentally ill woman held on her stomach after she tried to escape the back seat of a Cleveland police car; and Robert Minjarez, a cocaine user held down by Louisiana officers as he cried in an increasingly muffled voice, "I can't breathe."
Eric Garner, the New York City man whose chokehold death in 2014 became a flash point for protesters decrying the killings of unarmed black men by police, was also held down on his face. In addition to the chokehold, the medical examiner cited "prone positioning during physical restraint" as a cause of his death.
When the maneuver turns deadly, it's often because a suspect is disobeying commands or resisting, which can cause officers to apply even more pressure, said Harvey Hedden, executive director of the International Law Enforcement Educators and Trainers Association.
"In cases where people comply, there are other options," he said.
But often prone restraint is used on mentally ill or sick suspects whose duress is mistaken for resistance, escalating the problem, said Jamie Fellner, senior adviser for Human Rights Watch, which has studied use of force against mentally ill inmates.