The officer, Adam Coy, a 19-year veteran, was also charged with felonious assault and two counts of dereliction of duty.
Mr. Coy shot Andre Hill, 47, after responding to a call about a suspicious vehicle. When he and another officer arrived at the scene, Mr. Coy found Mr. Hill in a garage and opened fire within seconds. Mr. Hill, who was shot four times, died at a hospital shortly after.
Mr. Yost said his office acted as a special prosecutor in the case, reviewing evidence, interviewing witnesses and presenting charges to a grand jury, which indicted Mr. Coy on Wednesday.
“The vast virtue of law enforcement is diminished by the very few bad actors among its ranks, and only by holding a bad actor accountable can that virtue be sustained,” Mr. Yost said at a news conference. “Here’s what I mean in plain English: same rules for everybody.”
The dereliction of duty charges, Mr. Yost said, stem from the fact that Mr. Coy did not activate his body camera until after the shooting and that he failed to tell the other officer on the scene that he saw Mr. Hill as a threat.
The shooting was captured on video, however, because the body camera that Mr. Coy wore was equipped with a feature that captures the 60 seconds immediately before the camera is turned on. The camera did not capture audio during that initial minute, so any verbal exchange before the gunfire was not recorded.
“Truth is the best friend of justice, and the grand jury here found the truth,” Mr. Yost said. “Andre Hill should not be dead.”
Mayor Andrew Ginther of Columbus, who demoted the city’s police chief last week, thanked the grand jury for its service. “The indictment does not lessen the pain of his tragic death for Mr. Hill’s loved ones, but it is a step towards justice,” he wrote on Twitter.
Mr. Coy’s lawyer, Mark Collins, said that he had expected an indictment because of “the low threshold of probable cause,” but that the specific charges were surprising. He said the evidence would show that Mr. Coy was justified in his use of force and that the former officer believed that Mr. Hill was holding a silver revolver in his hand.
“Police officers have to make these split-second decisions, and they can be mistaken,” Mr. Collins said. “If they are mistaken, as long as there’s an honest belief and that mistake is reasonable, the action is justified.”
Mr. Coy will appear at a bail hearing on Thursday. He gave a written statement to the grand jury and a two-hour interview to the attorney general’s Bureau of Criminal Investigation.
The body camera footage of the shooting shows Mr. Coy and one other officer responding to a call about a suspicious S.U.V. parked in a residential area. As they approach a garage and shine a flashlight inside, Mr. Hill walks slowly toward them with what appears to be a cellphone in one hand. Within seconds, Mr. Coy opens fire and Mr. Hill falls to the ground.
Almost as soon as the shooting ends, the audio kicks in. Mr. Coy can be heard telling Mr. Hill to put his hands by his side and roll onto his stomach. The wounded man groans as Mr. Coy pats him down, saying, “Don’t move, dude.”
Based on the body camera footage, it is unclear how long officers waited before they provided first aid, but some officers are seen attending to Mr. Hill about six minutes after he was shot.
No weapon was recovered at the scene.