An independent autopsy commissioned for the family of George Floyd found that his death was a homicide and the unarmed black man died of “asphyxiation from sustained pressure” after a Minneapolis police officer held his knee on Floyd’s neck for several minutes and ignored his cries of distress, the family’s attorneys said Monday.

The results stated that Floyd’s death “was homicide caused by asphyxia due to neck and back compression that led to a lack of blood flow to the brain.”

That conclusion directly challenged preliminary results from the examination by the Hennepin County Medical Examiner’s Office saying that Floyd was not strangled, but died from other factors, including being restrained.

“George died because he needed a breath, a breath of air,” family attorney Ben Crump said on Monday afternoon at a news conference announcing the findings. “For George Floyd, the ambulance was his hearse.”