An autopsy sheds new light on what may have caused the Orlando shooter’s aggression

Forty-nine people were killed in the attack.

The gunman who killed nearly 50 people inside a gay nightclub in Orlando last month was on steroids.

RELATED: A partial transcript of Omar Mateen's 911 calls during the Orlando shooting has been released

Law enforcement officials say autopsy results indicate Omar Mateen's body showed signs of longtime exposure to steroids which can cause emotional shifts including anger, often called 'roid rage.

Marteen's ex-wife said he did have a history of steroid use.

It's not immediately clear if the drugs played a role in the June attack. More medical tests are underway.

RELATED: Orlando police just released new documents and now we have a play by play of the entire awful night

The Department of Justice is also looking into how the Orlando police responded to the Pulse nightclub shooting. The goal is to be able to provide other law enforcement officials with a guide about how to respond to similar incidents.

(H/T NY Daily News, Rare)