In hundreds of deaths where police used force meant to stop someone without killing them, officers violated well-known guidelines for safely restraining and subduing people - not simply once or twice, but multiple times.

Most violations involved pinning people facedown in ways that could restrict their breathing or stunning them repeatedly with Tasers, an Associated Press investigation found.

Some officers had little choice but to break policing best practices - safety guidelines that are recommended by government agencies, law enforcement groups and training experts - to save a life or protect someone.

Many other violations were harder to explain. Officers at times prematurely resorted to weapons or physical holds during routine calls or misread a person's confusion as defiance in medical emergencies, setting off a string of mistakes. In other cases, they kept applying force even after they had people handcuffed and controlled.

For its investigation, AP catalogued 1,036 deaths over a decade's time after officers had used force not involving their guns. In about half, medical officials ruled that law enforcement caused or contributed to the deaths, but they usually didn't mention whether policing best practices were followed.

Counting violations of best practices also was difficult when departments didn't document important details or withheld their files. But based on a review of tens of thousands of pages of police and court records, as well as hundreds of hours of body-camera video footage, AP found:

- Officers breached the guidelines in three or more ways in roughly 440 deaths, or about 45% of the time. In others, a single mistake sometimes fueled life-threatening injuries.

- Many who died were on drugs or alcohol, or had underlying medical conditions, making them more vulnerable to misapplied force, just as best practices forewarned.

- In about 30% of the deaths where police went outside the guidelines multiple times, the officers or bystanders were facing imminent or potential danger. Safety practices may excuse officers under those circumstances.

Because of how policing is set up in the United States, there are no national rules for how officers apply force. Best practices provide some direction but aren't mandatory. In the end, individual departments or states set their own policies and training.

Lethal restraint investigation

Many more people have died after police subdued them than the American public knows.

- The AP found that over a decade, more than 1,000 people died after police subdued them with physical force that is not supposed to be lethal. Explore the full database of cases here.

- Training failures can lead police to deadly use of a common tactic of handcuffing people when they're facedown.

- Dozens of deaths reveal the risks of injecting sedatives into people restrained by police.

Directives from the federal government would help establish consistent use-of-force standards, said Alex del Carmen, a longtime criminologist who has monitored court-ordered reforms at troubled departments and works at Tarleton State University.

While national policing organizations offer guidelines, they don't always trickle down to officers, and, he added, they "do not take the place of the federal government, who should have taken the lead many years ago in providing direction and clarity."

The reasons why officers didn't follow the guidelines varied, AP found. Some testified that they weren't taught them. In other departments, policies weren't up to date.

A few times, officers specifically credited their training with helping avoid mistakes. One Ohio deputy, for example, holstered his Taser after he was told a 60-year-old man wanted on a warrant had heart trouble.

Tyler Owen, a former officer, believes nearly all police do get it right. Most encounters don't involve force, he said, and the solution for avoiding trouble is almost always straightforward: Comply with police.

"By continuing to resist and continuing to fight law enforcement, you are putting yourself at risk," said Owen, now spokesperson for the Texas Municipal Police Association, the state's largest law enforcement group.

When officers deal with people who are volatile or can't comprehend commands, they sometimes need to use force outside best practices - even if that means "doing violent things to go home to their families," he said.

AP's investigation, done in collaboration with the Howard Centers for Investigative Journalism and FRONTLINE (PBS), covered 2012 through 2021. While violations spanned many types of "less-lethal force," the most prevalent happened in the four areas below.

Pinning facedown

What the guidelines say: Police have been on notice since the 1990s about the risks of pinning someone on their chest in what is known as prone position. The concern started with positional asphyxia - when the chest can't expand, starving the body of oxygen. But more recently, researchers have warned that compressing the chest also can stress the heart and cause cardiac arrest.

The key is getting someone off their stomach quickly. A 1995 Justice Department bulletin advised doing so "as soon as the suspect is handcuffed" and warned of a "vicious cycle" in which putting weight on a person's back can further restrict breathing, causing them to struggle more violently to create room for their lungs. That federal guidance came amid increasing concern about prone restraint, including from a national group of police chiefs in 1993.

The DOJ also has warned that prone restraint can be more dangerous to a broad category of people police often confront - those on drugs or alcohol. Also vulnerable are people who are obese, who have cardiac or respiratory problems, or who have already been shocked with stun guns. By 2001, the DOJ advised departments to develop policies addressing positional asphyxia.

What AP found: Officers restrained someone facedown in at least 740 of the 1,036 deaths - usually with one, or sometimes more, using their bodyweight. In about half of the prone restraint cases, police didn't turn over the person as soon as they were handcuffed or did so only after they had stopped responding.

Where video was available or police reports noted the duration of restraint, a few people were kept on their chests after handcuffing for less than 60 seconds. More often, the pinning continued for minutes while officers bound the suspect's ankles together or waited for them to stop struggling.

A video obtained by AP showed a police officer in Ava, Missouri, handcuffing a man having a drug relapse and restraining him in a prone position for roughly eight minutes. The officer warned he wouldn't ease up until the man stopped kicking. Once still, the officer asked the man, "Are you going to be calm now?" He didn't answer. Another two minutes passed before the officer realized the man didn't seem to be breathing. A federal judge who reviewed the video ruled in the officer's favor in a civil lawsuit, saying the law didn't require police to stop prone restraint once a person quit struggling. That legal interpretation, however, was out of step with federal courts in other regions, which provide broad direction on use of force.

About 240 of the prone restraint cases involved people suspected of using drugs or alcohol. For 11 minutes, officers in Gulfport, Mississippi, held down a 53-year-old man who was causing a disturbance outside a beachside restaurant. Police first shocked him with a Taser and then an officer straddled his back as he was pinned. Previously unreported dashcam video obtained by AP showed him struggling to shift his hips and shoulders, yelling "I can't breathe." He eventually became motionless with the officer still on top. The officer told investigators he'd been trained not to put someone on their chest and that his weight was on his knees, insisting - contrary to what the video showed - that he had turned the suspect sideways the entire time. A grand jury declined to charge the officers after the death was ruled accidental from drug use.

At least 180 people pinned to the ground were obese. Knox County deputies in Tennessee realized they needed to reposition a handcuffed man who was facedown in the dirt. "Roll him on his side so he can breathe. He's got a big belly," one said. But when the 280-pound man pulled his leg away, officers hog-tied him by crossing his legs, cuffing his ankles and strapping his hands and feet together behind his back. For more than three minutes, close to a dozen deputies stood by as he rolled on his stomach. One pressed a knee and hand into his upper back, forcing him to be still. A minute later, they saw his life was in danger when an officer kneeled next to his motionless body and asked his date of birth. His death was blamed on fentanyl and methamphetamines. The district attorney called the actions of deputies lawful and closed the case, but the family reached an undisclosed settlement with the county in a wrongful death lawsuit.

Too much taser

What the guidelines say: When stun guns began gaining popularity among police two decades ago, there were no specific limits for how many times, or how long, someone could be shocked. That changed as deaths and lawsuits against the leading brand of the weapon, Taser, increased.

Axon Enterprise Inc., the maker of Tasers, has long said that in volatile situations, Tasers are a safer alternative to shooting suspects or smashing their head with a baton. Tasers fire small darts that are connected to the weapon with wires, delivering electricity from a close distance that briefly locks up muscles. Officers can also drive Tasers into the body, painfully jolting someone to gain compliance.

The company has insisted that factors like drug intoxication or hidden cardiac problems are really to blame for deaths, not the electricity. But some research began finding repeated shocks can create cardiac and respiratory risks.

In 2011, the Police Executive Research Forum, a national law enforcement policy group, issued guidelines saying officers should be taught that multiple uses may increase the risk of death. The guidelines warned against simultaneous shocks from more than one device and recommended capping the electricity at 15 seconds - or three blasts of the standard 5-second cycle.

By 2013, Axon in its training manual warned to "avoid prolonged and repeated exposures" and cited the concerns from law enforcement and medical groups about going beyond 15 seconds.

Safety recommendations, including from Axon, also say officers should pause between pulling the Taser trigger to evaluate the person before delivering another shock. When multiple shocks aren't effective, officers should consider other options.

What AP found: Despite the warnings, officers fired their stun guns more than three times or for more than a combined 15 seconds in at least 180 of the 538 deadly encounters involving the weapons.

Three Roswell, New Mexico, officers shocked a 34-year-old man as many as 15 times after they said he was wielding a police-style baton and throwing handfuls of rocks. Some of the darts hit his head and chest. After an initial shot to the chest, the man dropped the baton, yet the stunning continued. A federal judge didn't find fault with the overall number of Taser shots but did say the final few when the man was on the ground and incapacitated went too far because he was no longer a threat.

In Colorado, one of two officers who fired their Tasers a combined eight times at a man resisting handcuffing testified in a lawsuit that he was not trained about the danger of shocking someone more than three times. The deputy chief of the Colorado Springs Police Department at the time testified that its policy allowed officers to keep delivering electricity until the person's behavior changed. The department determined the officers did nothing wrong, but the lawsuit alleging poor training of police is ongoing.

One of three officers in South Boston, Virginia, who shocked a man rolling on a hospital sidewalk said a suspect's actions - not Taser guidelines - dictate what to do. The officers fired their Tasers a combined 20 times, even after handcuffing the man. "There are eight pages of warnings, and basically if I read and abided by every single warning, I would not tase anyone," the officer said in response to a civil lawsuit later settled out of court. Federal prosecutors said they didn't see enough evidence to pursue civil right charges against the three officers.

Some cases went far beyond the guidelines issued by Axon and policing experts. Officers fired their stun guns 10 or more times in at least 29 encounters AP identified. In a rare occurrence, two police officers in Wilson, Oklahoma, were convicted of murder after shocking a man 53 times in 2019 - just under four minutes total of firing the Tasers - even though he never tried to attack either officer. A state investigator said the man was naked in a ditch and shocked numerous times because he apparently didn't follow orders to roll onto his stomach and put his hands behind his back.

Shocking the vulnerable

What the guidelines say: Axon and law enforcement organizations have warned police departments for well over a decade that the elderly and people having a mental health or medical crisis are among those at higher risk for sudden death from electrical shocks. Officers also have long been told that people on elevated surfaces or running could have a catastrophic fall when their muscles lock up.

In 2009, Axon first recommended that police aim Taser darts at the back or abdomen instead of the chest whenever possible. While the company said this would increase the weapon's "effectiveness and avoid the remote potential risk of cardiac effect," it said the main reason for the change was to defend against lawsuits, according to a company memo explaining the changes.

Many police agencies have adopted at least some of these recommendations, while still giving officers leeway when people pose an immediate danger and the need to control them outweighs the risks.

What AP found: The vulnerable groups most often subjected to shocks were suspected of using illicit drugs or showing signs of bizarre or aggressive behavior, paranoia, or unexpected strength.

Others were vulnerable in different ways. At least 10 people who died after stuns were 65 or older, including a veteran with dementia who had threatened to stab an officer with a pen at a Minnesota nursing home. The 79-year-old fell and broke his hip after the electrified darts connected. He died two months later from complications related to the fall. None of the officers faced an investigation, according to the Stillwater Police Department.

Officers shocked at least 50 people who were fleeing or susceptible to a fall. A federal court in Georgia said a DeKalb County police officer shouldn't have fired his Taser at an unarmed passenger who inexplicably ran from a traffic stop and then climbed onto an 8-foot wall. The court said the man had neither committed a crime nor made threatening gestures, yet the officer fired his Taser without giving a warning. The man fell, broke his neck and died.

In some cases, officers opted to use a Taser even when a gun might have been justified. Among the more than 100 people shocked by police in the chest, head, neck or genitals was a Michigan man who was sexually assaulting his girlfriend in front of her two children. Hearing him yelling "I'm going to kill her," one officer fired his Taser to stop the attack. Another shocked the suspect from 5 feet away as he was refusing to turn onto his stomach. That blast near his heart proved to be fatal, a medical examiner said. While the Rockwood Police Department's policy warned against targeting the chest, the officer said in a deposition that wasn't where he was aiming and the man was a moving target. He told a state investigator using the Taser was safer than "going hands on" with the man or using his firearm. A prosecutor and a federal court sided with the officers, citing the safety threat.

Force after cuffing

What the guidelines say: For the most part, federal courts have agreed that punching, using Tasers or holding someone facedown is excessive when they're handcuffed and not resisting or ignoring an officer's orders.

These federal court decisions have led many departments to adopt policies that allow force against handcuffed people in just a few instances. One model policy, developed by nearly a dozen law enforcement groups in 2017, called for using force against people in restraints only when they would otherwise flee or injure someone.

What AP found: Police failed to promptly turn over at least 360 people after they were handcuffed or controlled - about half of all cases involving prone restraint. Many of the officers also continued to use their bodyweight, hands or knees to apply pressure.

A federal appeals court said officers in Richmond, Virginia, went too far after they handcuffed and pinned a man who refused mental health treatment. After he became motionless, the officers still didn't let up, the court said. The court didn't fault the officers' decision to detain the man, but said he couldn't have posed a threat once he was outnumbered and handcuffed.

In more than 30 cases, police used Tasers in drive-stun mode or fired darts at someone who was already handcuffed or who had stopped resisting. Police officers in Hazelwood, Missouri, shocked a handcuffed man as many as 13 times and hit him repeatedly with a baton. The man was driving erratically on his way home to celebrate his wedding anniversary and appeared intoxicated. Prosecutors decided police did nothing wrong because he was aggressively resisting. A federal judge, who also sided with the police, said it was clear he fought for eight minutes, and that it took three officers and multiple Taser blasts and baton strikes to subdue him.

In a Delaware case, a federal judge wouldn't give a state trooper immunity from an excessive force claim after he fired his Taser at a man who appeared to be secured and no longer resisting. The trooper, a certified Taser instructor, initially took steps to avoid a deadly outcome when he came across the man, who had a gun behind his back. Thinking the man might be mentally ill, the trooper holstered his gun and shocked him, causing him to fall and drop his firearm. The trooper rapidly fired again because he thought the man was rolling over and reaching for the gun. But the third jolt of electricity was unjustified, the judge said, because it came 15 seconds later and after officers had secured the man. An expert hired by the family said the final blast hit the man's chest, something the trooper should have known to avoid.

From The Associated Press