The police had stopped Mr. Nichols, a 29-year-old FedEx worker and photographer, on the evening of Jan. 7 as he drove along a street near his mother’s house. The officers reported that he had been driving recklessly, though the police chief has since said the department could not find evidence of that.

Mr. Haley and other officers approached Mr. Nichols’s car, with at least one officer aiming his gun at the car. Mr. Haley, shouting obscenities, pulled Mr. Nichols out of the car while officers yelled conflicting orders and threatened to hurt him. “You guys are really doing a lot right now,” Mr. Nichols said as he lay on the pavement. “I’m just trying to go home.”

When Mr. Haley tried to pepper spray Mr. Nichols’s face, Mr. Nichols got up and ran away as another officer fired his Taser at him. A group of officers caught up with him several minutes later — less than 100 yards from his mother’s house — and repeatedly beat him for nearly three minutes.

Mr. Haley arrived to that second scene after officers had found Mr. Nichols and was not present for much of the assault. When he arrived, officers were in the process of handcuffing Mr. Nichols, who was groaning in pain, and had pinned him to the ground on his stomach. Even so, Mr. Haley ran up and delivered a strong kick to Mr. Nichols’s head or upper body.

Mr. Nichols was left bloody on the concrete, and he repeatedly fell over after officers propped him up next to a police car.

His death sparked protests in several cities after the videos were released, and the Memphis Police Department said it was disbanding the unit that the officers had been assigned to. Known as Scorpion, it was created to target neighborhoods with high crime rates. The department also suspended two officers, one of whom had fired the Taser at Mr. Nichols as he ran away. Later, as that officer’s body camera continued rolling, the officer said, “I hope they stomp his ass.”

At the council hearing, Chief Davis said that the seven additional officers facing discipline, who have not been identified, included several who had not actually been at the scene of the assault. She said the department struggled from a lack of supervisory staff, saying that it was a bigger problem than training and that the department had been short on higher-ranking officers for years.