A medical examiner has classified George Floyd's death as a homicide.
A private post-mortem said his heart stopped as police restrained him and suppressed his neck, in a widely seen video that has sparked protests across the US.
The report found that Floyd “experienced a cardiopulmonary arrest while being restrained by law enforcement officer(s).”
The post-mortem examination, commissioned for Mr Floyd's family, found that he died of asphyxiation due to neck and back compression.
"The cause of death in my opinion is asphyxia, due to compression to the neck - which can interfere with oxygen going to the brain - and compression to the back, which interferes with breathing," said Michael Baden, one of two medical examiner’s who carried out he report.
Bystander video showed officer, Derek Chauvin, who has since been charged with murder, holding his knee on Mr Floyd's neck despite the man's cries that he cannot breathe until he eventually stopped moving.
How does the report differ from the county medical autopsy?
The family's procedure differs from the official post-mortem as described in a criminal complaint against the officer.
That autopsy included the effects of being restrained, along with underlying health issues and potential intoxicants in Mr Floyd's system, but also said it found nothing "to support a diagnosis of traumatic asphyxia or strangulation".
The family's post-mortem was conducted by Michael Baden and Allecia Wilson. Mr Baden is the former chief medical examiner of New York City, who was hired to conduct a post-mortem of Eric Garner, a black man who died in 2014 after New York police placed him in a chokehold and he pleaded that he could not breathe.
What is asphyxia?
Asphyxia occurs when your body is deprived of oxygen and can be life-threatening.
Physical or mechanical asphyxia is what happens when an object or force prevents a person from breathing.
Ilnesses, such as heart failure, can also cut off the supply of oxygen and lead to asphyxia.
At least 5,600 people have been arrested as protests continue across the United States following the death of George Floyd in Minneapolis.
In Washington DC law enforcement officers used tear gas, pellets and low-flying helicopters to turn back demonstrators in the US capital.
Protesters remained on the streets well past the 7pm curfew that had been imposed by District of Columbia mayor Muriel Bowser. They had spent hours marching peacefully around the city before they were buzzed by the helicopters.
The scenes in DC came as President Donald Trump threatened to deploy the military if state governors failed to stamp out protests.