The family of George Floyd and their lawyers on Monday called for a first-degree murder charge to be filed against former Minneapolis cop Derek Chauvin after a new independent autopsy found that Floyd died as the result of asphyxiation from sustained pressure on his neck and back.

Floyd’s family and lawyers also called for the officers who were with Chauvin as he knelt on Floyd’s neck for more than eight minutes should also be criminally charged, although lawyers did not specify what those charges should be.

“They knew that they were applying restraints that could or would cause death,” said Antonio Romanucci, one of the lawyers for Floyd’s family. “They are criminally liable because they knew what they were doing could lead to death.”

Chauvin was charged with third-degree murder last week after an official autopsy suggested that Floyd’s underlying heart conditions, combined with the police restraint and “potential intoxicants in his system,” likely contributed to his death.

But Dr. Michael Baden, one of the pathologists who performed the independent autopsy, at a press conference Monday said, “Mr. Floyd had no underlying medical problems that caused or contributed to his death.

The autopsy found that Floyd’s death was a “homicide caused by asphyxia due to neck and back compression that led to a lack of blood flow to the brain,” according to a statement issued by the family’s lead attorney Ben Crump.

“Sustained pressure on the right side of Mr. Floyd’s carotid artery impeded blood flow to the brain, and weight on his back impeded his ability to breathe,” the statement said.

“The independent examiners found that weight on the back, handcuffs and positioning were contributory factors because they impaired the ability of Mr. Floyd’s diaphragm to function.”

Baden addressed the fact that Floyd repeatedly said, “I can’t breathe” as Chauvin knelt on his neck.

“Police have this false impression that if you can talk, you can breathe. That’s not true,” said Baden, who conducted the autopsy with Dr. Allecia Wilson.

Crump said, “For Chauvin to leave his knee on George’s neck despite warnings and evidence that his life was in danger — and to continue that course for many minutes — demands a first-degree murder charge,

Floyd’s death has ignited protests nationwide.

Crump and Floyd’s family said people should continue to protest, but urged them to not engage in violence or looting.

Chauvin and three other officers — all of whom have since been fired — detained and arrested Floyd on suspicion that he had used a counterfeit bill to make a purchase.

A criminal complaint, released Friday accuses Chauvin of keeping his knee pressed down on Floyd’s neck for eight minutes and 46 seconds, including for nearly three minutes after Floyd was unresponsive. -CNBC