The family of a black man fatally shot by police in Charlotte, North Carolina, have released its own video of the encounter that sparked three days of protests and continued to urge officials to release their own recordings of the slaying.

The moment that a black police officer shoots Keith Scott, a 43-year-old father of seven, cannot be seen in the two-minute video recorded by his wife, Rakeyia, who can be heard urging officers not to open fire on her husband.

"Don't shoot him! He has no weapon," she can be heard telling officers as they yell at Scott to "Drop the gun!"

About a half-dozen gunshots can be heard in the video released to US media, followed by her scream: "Did you shoot him? He better not be dead."

Scott's death was the latest in a long string of controversial killings of black people by US police that have stirred an intense debate on race and justice.

A United Nations working group on Friday compared the killings to the lynching of black people by white mobs in the 19th and 20th centuries.

The UN working group recommended the US create a reliable national system to track killings and excessive use of force by law enforcement officials, as well as ending the practice of racial profiling.

Scott's death sparked two days of rioting in North Carolina's largest city, with protesters dismissing the claim of police officers that Scott was holding gun.

Charlotte-Mecklenberg Police Chief Kerr Putney has said video taken by police body cameras supports the police's version of events but has refused to release the video publicly.

He told reporters on Friday that releasing the video now could harm the investigation into the shooting, now being led by the state.

Scott's family, initially contended that he was carrying a book, but after viewing the police video on Thursday said it was "impossible to discern" what, if anything, he was carrying.

No gun can be seen in Scott's video, which was filmed from a nearby curb as the drama unfolded on the street in front of her.

Police arrested a civilian on Thursday and charged him with the murder of a protester who was shot during Wednesday night's protest and died on Thursday, Charlotte-Mecklenberg Police Chief Kerr Putney told a press conference on Friday.

Police identified the shooter as Rayquan Borum, 21, and the victim as Justin Carr. They did not disclose Carr's age.

In contrast to the tension in Charlotte, the city of Tulsa, Oklahoma, was calm after a white police officer was charged with first-degree manslaughter on Thursday for the fatal shooting of an unarmed black man that was also captured on video.

The officer involved in that shooting turned herself in early on Friday and was released on $US50,000 ($A66,000) bond.