Three police officers present when their colleague knelt on George Floyd’s neck for more than eight minutes are to face charges.
Prosecutors have also upgraded the charges against the main officer involved, Derek Chauvin, to second-degree murder.
He had initially been charged with third-degree murder and second-degree manslaughter over Mr Floyd’s death, which has triggered protests across the US and around the world.
Minnesota Attorney General Keith Ellison said: “I believe the evidence available to us now supports the stronger charge of second-degree murder.”
All four Minneapolis officers had been fired after Mr Floyd’s death on 25 May, but the three were not immediately charged.
Mr Ellison said Thomas Lane, J Kueng and Tou Thao will stand accused of aiding and abetting second-degree murder.
“I strongly believe that these developments are in the interests of justice for Mr Floyd, his family, our community and our state,” he added.
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He went on to thank people for their patience with prosecutors to date and appealed for further patience as the cases progress.
Lawyer Ben Crump tweeted that the Floyd family was “deeply gratified” by Mr Ellison’s action and called it “a source of peace for George’s family in this difficult time”.
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The criminal complaint against Chauvin said: “Officer Chauvin’s restraint of Mr Floyd in this manner for a prolonged period was a substantial causal factor in Mr Floyd losing consciousness, constituting substantial bodily harm, and Mr Floyd’s death as well.”
Some of the disorder seen in the days since Mr Floyd’s death dissipated on Tuesday night, with no major reports of violence as demonstrations continued around the US.
Curfews and efforts by protesters to contain any clashes were credited with preventing more widespread damage to businesses in New York and other cities overnight.
New York mayor Bill de Blasio said: “Last night we took a step forward in moving out of this difficult period we’ve had the last few days and moving to a better time.”
The city’s police said they arrested about 280 people on protest-related charges on Tuesday night, compared with 700 a day earlier.