George Floyd, whose fatal encounter with Minneapolis police stirred a global outcry over racial bias by US law enforcers, tested positive for the coronavirus.
But there was no indication Covid-19 played a role in his death. The cause of death was cardiopulmonary arrest while Floyd, 46, was being restrained by police on May 25.
A coroner also ruled his death a homicide.
Four police officers since fired from their jobs for their roles in a killing seen on a bystander's phone are now on new charges.
Derek Chauvin, 44, faces a second-degree murder count and a manslaughter charge.
He was the one who knelt on Floyd's neck for nearly nine minutes as the victim groaned repeatedly "please, I can't breathe." Floyd was pronounced dead a short time later.
Thomas Lane, Alexander Kueng and Tou Thao, the three other now-fired officers, are charged with aiding and abetting second-degree murder and manslaughter.
Aiding and abetting second-degree murder carries the same maximum punishment as the underlying offense - 40 years in prison.
The autopsy report, in listing cardiopulmonary arrest as the cause of death, also cited "complicating law enforcement subdual, restraint and neck compression."
It listed several additional factors as "significant conditions" contributing to Floyd's death, including heart disease, high blood pressure and intoxication from the powerful opioid fentanyl plus recent methamphetamine use.
The report said a nasal swab sample from Floyd's body tested positive for Covid-19. He also tested positive on April 3, nearly eight weeks before his death.