Andre Maurice Hill, 47, was killed in Columbus, a city in Ohio, on the night of Monday through Tuesday, while in the garage of a house.
Prosecutions for serious misconduct will be launched against the police officer responsible for the shots, with a view to his dismissal.
A black man has been killed by a white policeman in Columbus, Ohio, the second in a matter of weeks in the northern city of the United States, sparking outrage in a country crossed since the spring by a historic movement against the police violence.
Andre Maurice Hill, 47, was in the garage of a house on the night of Monday to Tuesday when he was hit by several bullets by the police officer.
The police had been called on the spot for a minor incident.
The officer's pedestrian camera footage shows Andre Hill walking towards the officer holding a cell phone in his left hand, his other hand remaining invisible.
Seconds later, the agent fires and Hill collapses.
No sound comes to explain the circumstances of the shots.
Adam Coy and his colleague, will wait several minutes before approaching the victim, then still alive and who will die later.
"Immediate action"
City Police Chief Thomas Quinlan announced Thursday that an internal serious misconduct lawsuit will be launched against the shooting officer, Adam Coy, with a view to his dismissal.
The agent, who has been suspended since the facts, is to be heard Monday by the city's director of public security, Ned Pettus, who will rule on his fate.
"We have an officer who violated his oath to abide by the rules and policies of the Columbus police," Thomas Quinlan said in a statement.
"And the consequences of this violation are such that they demand immediate action. This violation has cost an innocent person his life."
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According to local media reports, the officer has already been the subject of complaints of excessive use of force.
The Ohio Criminal Squad has for its part opened a judicial investigation.
Another murder three weeks ago
A few dozen people demonstrated Thursday afternoon in the neighborhood where Andre Hill was killed, to denounce police violence against African Americans and demand justice.
Andre Hill, who was unarmed, is the second African American to be killed by police in less than three weeks in Columbus.
Casey Goodson Jr., 23, was shot several times on December 4 as he returned home from shopping for sandwiches.
"Once again, agents see a black man and conclude that he is a dangerous criminal", indignant Wednesday lawyer Ben Crump, who defends several families of victims including that of George Floyd.
The latter's death at the end of May sparked a wave of protests against racism and police violence in the country.
Andre Hill is the 96th black victim of a police officer since George Floyd, he added, denouncing a "tragic succession" of fatal incidents involving police officers.