George Floyd and Derek Chauvin, the former police officer accused of killing him, knew each other and were involved in an altercation at a nightclub where they worked, according to a former collegue.
Mr Chauvin, 44, has been charged with murder over the death of Mr Floyd, 46, in Minneapolis on May 25 after he knelt on his neck for nearly nine minutes. The video of the killing sparked protests around the world.
Chauvin and Floyd worked in security at a nightclub at the same time. David Pinney, a former co-worker, said the two men had a history and claimed they knew each other "pretty well".
David Pinney told CBS News: "They bumped heads."
"It has a lot to do with Derek being extremely aggressive within the club with some of the patrons, which was an issue," Mr Pinney explained.
The Floyd family's lawyer has called for Chauvin, who faces a charge of second-degree murder, to have his charges upgraded to first-degree murder "because we believe he knew who George Floyd was".
Maya Santamaria, the owner of the club, which was torched by protests in the city, described to CBS News how Chauvin treated black customers. Ms Santamaria said she had employed Chauvin, when he was off-duty from his role as a police officer, to sit in his police car outside El Nuevo Rodeo for 17 years.
Ms Santamaria said Floyd frequently worked as a security guard at the club in the past year. She said both men worked on Tuesday nights
Asked if she thought that Chauvin had a problem with black people, Ms Santamaria said: "Yeah, I think he was afraid and intimidated."
Meanwhile, a prison guard has been suspended after taking part in a re-enactment mocking the killing of Floyd which was captured on video.
A group of white men acted out the killing, one kneeling on another's neck, in front of a US flag and a Donald Trump banner.
The New Jersey Department of Corrections said one of its officers was involved in the "hateful and disappointing video".
