Disturbing police body camera footage released Wednesday shows a man being restrained by Dallas officers before his death and yelling, "You're gonna kill me!"

The footage showing the August 2016 death of Tony Timpa in Dallas shows an officer pinning him to the ground with his hands cuffed behind him for nearly 14 minutes as the 32-year-old eventually becomes unresponsive. Officers are heard joking that Timpa had fallen asleep, with one yelling "five more minutes, mom!"

Timpa's death in the parking lot of an adult video store came after he called 911, saying he was off his medication for schizophrenia and depression and needed help. Questions about what happened in the moments leading to his death have swirled as city officials argued against the release of the body camera footage, according to the Dallas Morning News, but a judge on Monday sided with news outlets who had sought to make the video public.

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In a federal lawsuit alleging excessive force, Timpa's family claims the officers "recklessly" and "knowingly" killed the man.

Tony Timpa CBS DFW

"He was expecting someone to help him, that's why he called," Timpa's mother Vicki Timpa told CBS Dallas / Fort Worth in 2018, after the family had viewed the body camera footage but before it was made public. "He wasn't expecting several police to kill him."

A medical examiner ruled Timpa's death a homicide, and listed the cause as "sudden cardiac death" caused by "the toxic effects of cocaine and physiological stress associated with physical restraint," reports CBS DFW. Sgt. Kevin Mansell, Officer Danny Vasquez and Officer Dustin Dillard were indicted on misdemeanor deadly conduct charges in December. But the Dallas County District Attorney's office dismissed the charges in March, saying three medical examiners had concluded the officers' conduct was not reckless.

The three officers were placed on administrative leave but returned to full duty in April, according to Dallas police. Dallas police said Vasquez and another officer, Raymond Dominguez, were disciplined for "being discourteous and unprofessionalism."

The department wouldn't comment on the video because of the pending litigation.

Police incident reports cited by the Morning News say Timpa's behavior was aggressive and combative, but the video shows Timpa writhing as he apparently struggles to breathe, repeatedly asking the officers to stop restraining him. He's heard yelling, "Help me!"

Timpa was unarmed and had already been handcuffed by a private security guard before officers arrived, the paper reports.

As Timpa becomes unresponsive, an officer says he appears to be "out cold," and they laugh and joke about him being asleep, saying, "It's time for school, wake up!"

Another says, "I don't want to go to school! Five more minutes, Mom!"

Paramedics are seen administering a sedative and transferring him onto a gurney and into an ambulance. Timpa is apparently unresponsive. One of the officers asks: "He didn't just die down there, did he?" and "Hope I didn't kill him."

Paramedics later inform the officers that Timpa has died.

Speaking last year to CBS DFW, Dallas Police Association president Michael Mata said the officers followed department policy and their actions had nothing to do with Timpa's death.

"My heart goes out to his mother," Mata said. "I would hate to lose a child but what killed that man was 20 years of drug abuse."

Vicki Timpa told CBS DFW that her son struggled with alcohol and drugs, but called Mata's statement an "absurd falsehood."

An attorney for Timpa's family, Geoff Henley, told CBS DFW on Wednesday that officers had no reason to use that kind of restraint for that long.

"Tony Timpa shouldn't have died that night," Henley said.