A former Columbus police officer who fatally shot a Black man in December has been arrested and charged with murder, Attorney General Dave Yost of Ohio announced on Wednesday.

The former officer, Adam Coy, a 19-year veteran, was also charged with felonious assault and two counts of dereliction of duty. He was fired several weeks after the shooting.

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 had been holding a cellphone, 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. The grand jury indicted Mr. Coy, who was arrested 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 first minute, so any verbal exchange before the gunfire was not recorded.

Mr. Coy will appear at a bail hearing on Thursday.

“Truth is the best friend of justice, and the grand jury here found the truth,” Mr. Yost said. “Andre Hill should not be dead.”

This is a developing story and will be updated.