VIDEO: The 15-year Phoenix firefighter and decorated soldier who was found dead July 8 while on duty at the Arizona Army National Guard Base died of a drug overdose involving opioids, investigators confirmed Friday. Juston Doherty, 45, died of an overdose involving oxycodone and fentanyl coupled with diazepam — also marketed as Valium — and alcohol, according to a report released Friday by the Maricopa County Office of the Medical Examiner. The medical examiner ruled the death was accidental. He was found dead in his room several hours after he was last seen doing physical training for his reserve duty with the National Guard, investigators said.