The medical examiner said it was impossible to know which bullet killed Jayland Walker, or how many shots were fired in total.
The report comes two days after hundreds mourned his death in the city of Akron, which remains on edge.
Officials have announced a curfew on Friday night amid near-daily protests.
According to the medical examiner, Walker sustained serious injuries to his heart, lungs and arteries in the 27 June shooting in the city of Akron.
He was killed at the end of an attempted traffic stop that began over minor equipment violations and quickly devolved into a roughly six-minute pursuit.
Authorities have said he fired a single shot 40 seconds into the chase.
Police body camera footage shows Walker, in a ski mask, jumping out of the moving vehicle from its passenger side and ducking into a parking lot where police opened fire on him from multiple directions.
The footage is too blurry to accurately determine what authorities called a “threatening gesture” he made before he was shot.
However, Walker was unarmed at the time and his family, through lawyers, have said there was no need to kill him.
Police found an unloaded handgun, one clip of ammunition and a wedding band in the driver’s seat of his vehicle.
Initial findings showed more than 60 wounds on Walker’s body. Summit County medical examiner Dr Lisa Kohler said it was “very possible” one bullet may have caused multiple entrance wounds.
The eight officers involved in the shooting – seven of whom are white, and one of whom is black – are on paid leave as the state of Ohio investigates.
Their local police union has said it believes the officers thought they were at immediate risk of serious harm and acted in line with their training.
On Thursday, the National Association for the Advancement of Colored People, a civil rights organisation, made a direct plea to US Attorney General Merrick Garland, the country’s top prosecutor, to open a federal investigation into the incident and hold the officers accountable “to the fullest extent of the law”.
The prosecution rate for US police officers in fatal shootings remains low, but recent cases have recast the conversation.
The Minnesota officer who fatally shot 20-year-old Daunte Wright last April was charged with manslaughter, and the Michigan officer who shot 26-year-old Patrick Lyoya in the head this April is facing murder charges. Both incidents began as traffic stops.