Quinlan expedited the investigation and bypassed procedure to file two departmental charges alleging critical misconduct against Coy in the death of Hill.
"This is what accountability looks like. The evidence provided solid rationale for termination," Quinlan said after Coy's termination Monday afternoon. "Mr Coy will now have to answer to the state investigators for the death of Andre Hill."
Members of the local Fraternal Order of Police attended the hearing on behalf of Coy, who was not in attendance, according to a statement from Pettus' office.
"Officer Coy was given the opportunity today to come and participate," Brian Steel, vice-president of the police union, told reporters Monday. "He elected not to participate. I do not know why ... I would have liked to have him here, but it's his decision."
Coy and another officer responded to a neighbour's non-emergency call after 1am Tuesday about a car in front of his house in the city's northwest side that had been running, then shut off, then turned back on, according to a copy of the call released Wednesday.
Mayor Andrew Ginther said it remains unclear if that car had anything to do with Hill.
Police bodycam footage showed Hill emerging from a garage and holding up a cellphone in his left hand seconds before he was fatally shot by Coy. There is no audio because the officer hadn't activated the body camera; an automatic "look back" feature captured the shooting without audio.
Hill lay on the garage floor for several minutes without any officer on the scene coming to his aid.
An investigation is also being conducted into the other officers who responded to the call that ended in Hill being shot, who Quinlan said also appear to have either failed to activate their body cameras or to render Hill aid. He said any others who violated department protocols will be held accountable.
Officers must activate their body cameras as soon as they are dispatched to a major incident such as a shooting, robbery or burglary, under departmental policy. Although Coy was dispatched on a non-emergency call, the call became an enforcement action when the officer interacted with Hill because that was separate from the original call, said police department spokesman Sergeant James Fuqua.
In addition to an internal police investigation, Ohio Attorney-General Dave Yost was appointed a special prosecutor in the death of Hill on Thursday.
There is also an investigation under the state's criminal investigations unit, under Yost, with assistance from the US attorney's office and the FBI's Civil Rights Division.
Coy, a 17-year member of the force, was relieved of duty, ordered to turn in his gun and badge, and stripped of police powers last week.
The killing of Hill at the hands of Columbus police follows the fatal shooting of Casey Goodson Jr on December 4 by a white Franklin County Sheriff's deputy. The two back-to-back shootings have resulted in an outpouring of criticism from advocates and the Black community in Columbus for wider and more comprehensive police reform.
"The termination of Adam Coy from Columbus Division of Police does not bring Andre Hill back to those who love him," Ginther said in a statement Monday.
Hill's family issued a statement through attorney Ben Crump's law firm, calling the decision to fire Coy "correct" but urging law enforcement to do more.
"We need to redefine a relationship between police and communities of colour in which it doesn't turn deadly for a Black person with a cell phone to encounter a law enforcement officer," the statement said.
