MINNEAPOLIS (AP) — The family of George Floyd says an independent autopsy has found that he died of asphyxiation from sustained pressure on his back and neck.

Floyd, a black man who was in handcuffs at the time, died a week ago after a white Minneapolis officer held his knee on Floyd’s neck for several minutes. The officer ignored bystander shouts to get off him and Floyd’s cries that he couldn’t breathe. The family’s autopsy differs from the official autopsy as described in a criminal complaint that ruled out asphyxiation or strangulation.

Attorney Ben Crump says Officer Derek Chauvin should be charged with first-degree murder.

(Story written by AMY FORLITI and STEVE KARNOWSKI/AP)