An autopsy released this morning ruled the death of UNC assistant track and field coach Antonio Pettigrew to be a suicide.

Pettigrew was found dead in his car in Chatham County early the morning of Aug. 10. He was 42 years old.

The report written by the N.C. Office of the Chief Medical Examiner lists the official cause of death as diphenhydramine toxicity.

Diphenhydramine is used to treat allergies and sleep loss, and is the active ingredient in Unisom, a sleeping pill that Pettigrew had an open bottle of in his car the morning he was found.

The investigation report said that Pettigrew had been having stress at work and that he had suffered neck and prostate problems prior to his death.

A graduate of St. Augustine’s College in Raleigh, Pettigrew had spent three years as director of cross country and track and field at Raleigh’s Cardinal Gibbons High School before coming to UNC. At UNC, he specialized in coaching the team’s sprinters, hurdlers and relay teams.

In his professional career, Pettigrew won a gold medal at the 2000 Summer Olympics as a member of the U.S. 1,600-meter relay team. However, the International Olympic Committee stripped the team of its gold in 2008 after Pettigrew admitted during the trial of his former coach Trevor Graham to taking performance-enhancing drugs.

Pettigrew is survived by his wife, Cassandra, and their son, Antonio Jr.