Columbine survivor and addiction recovery advocate Austin Eubanks died of a heroin overdose last month, an autopsy report from the Routt County Coroner’s Office said.

Eubanks, 37, was found dead May 18 in his Steamboat Springs home. He was a nationally-recognized addiction and recovery speaker, previously overcoming his own battle with painkillers following the 1999 Columbine massacre. He survived a gunshot wound but lost his best friend in the shooting.

“As an injured survivor of the Columbine shooting, Austin’s traumatic experience as a teen was the catalyst to his painful journey through addiction,” his website stated. “He has since devoted his career to helping those who have turned to substances as a result of trauma.”

His death was ruled an accident by “acute heroin toxicity,” according to the report. Eubanks had a history of opioid addiction and illicit drug abuse, the report said. Eubank’s father found him unresponsive on the day of his death, the report stated.

Eubanks’ family set up a memorial fund in his name and is collecting tax-deductible donations at austineubanks.com. In partnership with The OnSite Foundation, a nonprofit that provides counseling and emotional health education, the family is launching a therapeutic program for survivors of mass violence.

“Austin cared deeply about his family and close friends and fought a personal battle every day to bring light, hope and healing to others,” his sister Hayley Eubanks said in a statement. “He encouraged us all to lean in to the pain, and through this much-needed therapeutic program, his voice will continue to be heard and healing will begin.”