A lawyer for the family of George Floyd, whose death sparked unrest across the US, has accused a police officer of "premeditated murder".
Minneapolis policeman Derek Chauvin has been charged with third-degree murder, but lawyer Benjamin Crump told CBS news it was a case of first-degree murder.
"We think that he had intent... almost nine minutes he kept his knee in a man's neck that was begging and pleading for breath," he said.
Several US cities have imposed curfews.
The Floyd case has reignited US anger over police killings of black Americans. It follows the high-profile cases of Michael Brown in Ferguson, Eric Garner in New York and others that have driven the Black Lives Matter movement.
"The fact that officer Chauvin kept his knee on his neck for almost three minutes after he was unconscious. We don't understand how that was not first degree murder. We don't understand how all these officers haven't been arrested," lawyer Crump said.
Three other officers present at the time have also since been sacked.
For many the outrage over George Floyd's death also reflects years of frustration over socio-economic inequality and segregation, not least in Minneapolis itself.
In video footage, Mr Chauvin, 44, can be seen kneeling on Mr Floyd's neck for several minutes on Monday. Mr Floyd, 46, repeatedly says that he is unable to breathe.
There have been five nights of arson and looting in Minneapolis and the adjacent city of St Paul. Minnesota's Governor Tim Walz said on Saturday he was deploying the full Minnesota National Guard for the first time since World War Two.
Governor Walz said racism in his state had created the conditions for Mr Floyd's death.
www.bbc.com/news/world-us-canada-52869504
