Mannella fired three shots through the front windshield of Burroughs car, hitting him in the chest each time.
A Trumbull County grand jury heard from 25 witnesses, according to the 35-page report.
Both officers said they fired because they feared Burroughs was about to drive straight into officer Manella with his vehicle.
Mannella had gone to the complex looking for Burroughs after an alleged earlier run-in with a probation officer who tried to arrest Burroughs at Niles Municipal Court.
The court had called police and reported Burroughs resisted arrest on two warrants and left the building, then when the probation officer attempted to stop Burroughs from leaving the 35-year old put his car in reverse and allegedly struck the court officer.
According to the report, Mannella told investigators with the Ohio Bureau of Criminal Investigations that he yelled stop, get out of the car: stop get out of the car, not even a hand off the wheel, nothing, just started heading and came right at me. At that point I thought, he's just going to hit me, and I can't have him run me over.
Another officer also fired shots, but those bullets did not hit Burroughs.
Ohio's top law enforcement agency, Ohio Bureau of Criminal Identification and Investigations conducted it's investigation interviewing witnesses and reviewing video body camera video. Its report was 1500 pages.
A community conference is set for Saturday in front of the Niles Police Station by people saying Burroughs should have had his day in court.