President Joe Biden is urging protests in Tennessee to remain peaceful as officials plan to release video of an arrest that led to a motorist's death.
Five Memphis police officers have been fired and are facing murder charges after Tyre Nichols, 29, died three days after a traffic stop on 7 January.
Bodycam footage of the encounter is expected to be made public on Friday evening local time. Lawyers for the Nichols family said it will show him being severely beaten.
"I'm sickened by what I saw," Tennessee Bureau of Investigation director David Rausch said on Thursday after reviewing the footage, describing the officers' actions as "absolutely appalling".
The city of Memphis is reported to be on edge and police have stepped up patrols there as they prepare for possible demonstrations.
Mr Nichols, a black man, was stopped by five police officers, who are also black, on his way home after taking photos of a sunset at a local park, an attorney for the family said.
A lawyer for Mr Nichols' family said the bodycam footage showed Mr Nichols being pepper-sprayed, tasered, restrained and kicked.
All five of the officers face charges of second-degree murder, aggravated assault, aggravated kidnapping, official misconduct and official oppression.