A grand jury has indicted five former police officers on murder and other charges in connection with the death of Tyre Nichols.
US President Joe Biden called for any protests to be peaceful following the charges on Thursday.
Nichols, 29, died in hospital three days after a confrontation during a traffic stop in the US city of Memphis, Tennessee, on 7 January.
The father of one had been arrested after being stopped for reckless driving, police said, before being allegedly beaten by the officers for three minutes.
Five black officers involved in the arrest were subsequently sacked after a police investigation found they used excessive force or failed to intervene and help him.
Officials are expected to release bodycam footage of the incident on Friday evening.
“We’re here today because of a tragedy that wounds one family deeply but also hurts us all,” district attorney Steve Mulroy said at a news conference.
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He added that the five officers have been charged with second-degree murder, aggravated assault, aggravated kidnapping and official misconduct.
The Memphis Police Department identified them as Tadarrius Bean, Demetrius Haley, Emmitt Martin III, Desmond Mills, Jr, and Justin Smith, who are all black and aged between 24 and 32.
Each officer had served with the department for around two and a half to five years, and were dismissed from the force last Saturday.
Meanwhile, two Memphis Fire Department employees who were involved in the response were also relieved of their duties during an investigation, a department spokesperson said earlier this week.
President Biden said in a statement: “Outrage is understandable, but violence is never acceptable.
“Tyre’s death is a painful reminder that we must do more to ensure that our criminal justice system lives up to the promise of fair and impartial justice, equal treatment and dignity for all.”
Memphis Police Chief Cerelyn Davis said on Wednesday that other police officers remain under investigation for police infractions.
In a video shared on YouTube, she asked for calm when the bodycam footage is made public.
“I expect you to feel what the Nichols family feels. I expect you to feel outrage in the disregard of basic human rights,” she said.
“I expect our citizens to exercise their First Amendment right to protest, to demand action and results, but we need to ensure our community is safe in this process.”
Several recent incidents of police brutality against black people in the US have sparked outrage and calls for reforms in policing.
US correspondent
America has been here before. A black man dead at the hands of police officers, brutality captured on camera.
Rodney King and George Floyd are just two names that define a deadly dysfunction in the institution that exists to protect and serve.
Now add Tyre Nichols – 29 years old, a father and family man who worked at FedEx and enjoyed skateboarding. “Nobody’s perfect,” said his mother RowVaugn. “But he was damn near.”
We are told the events leading up to his death are contained in a video lasting an hour, multiple angles of what has been trailed as a savage assault.
A lawyer for the Nichols family spoke of him being beaten “like a human pinata”. The Friday night release of the footage is shrouded by a sense of dread.
Experience shows it is shocking video content of a sort liable to ignite violent street protests and, in Memphis, they are aware of the danger. It explains why the build-up to the release of the footage has been choreographed around charges for the police officers involved.
In a place where the public demands accountability, laying charges of second-degree murder will go a considerable distance towards matching expectations. Murder in the second degree accuses the officers of knowingly killing Mr Nichols.
Does it make a difference that the five men in uniform were black? Perhaps. Time will tell if, and how, that plays into the wider public response.
Much of the reaction, so far, has focused on the power that police have and the inclination to abuse it with deadly consequences. In video form, evidence of it will soon be laid bare – and Memphis is braced.
The Nichols family watched the police footage on Monday with their lawyer, Ben Crump, who compared the beating to the 1991 Los Angeles police assault on Rodney King that was captured on video and sparked protests and police reforms.
“He was defenceless the entire time. He was a human pinata for those police officers,” Antonio Romanucci, Mr Crump’s co-counsel, told reporters.
Mr Crump said Nichols’ last words heard on the video were of him calling for his mother three times.
