Jeff Conaway's death on May 27 was ruled as accident and caused by major internal infection, according to the autopsy as reported by the Associated Press.
The former star of "Taxi" and "Grease" died at age 60 after he was taken off life support following a battle with pneumonia and sepsis in a Los Angeles-area hospital.
The Los Angeles County coroner said that a toxicology test was not conducted because the actor had been hospitalized before his death, so his blood would have come back clean. However, when Conaway entered the hospital he did have opiates and other drugs in his system.
The actor was rushed to a hospital on May 11 and was put in a medically-induced coma while doctors worked to treat his ailments.
Conaway played Kenickie, a member of the T-Birds clique and friend to John Travolta's Danny in the 1978 musical film "Grease" and portrayed Bobby Wheeler on the television show "Taxi," which also starred late comedian Andy Kaufman and ran between 1978 and 1983.
There was a slight controversy in September when Conaway was left out of the "In Memoriam" montage at the Emmy Awards.
Earlier reports had said Conaway had been hospitalized after suffering an overdose, which Dr. Drew Pinsky, who treated Conaway on the reality show "Celebrity Rehab with Dr. Drew," has denied.
"There is no evidence showing Jeff died from an overdose," Pinsky said in a statement to OnTheRedCarpet.com "This was aspiration with overwhelming pneumonia and sepsis. Jeff is another example of a pharmaceutical death from the overutilization of prescription drugs. Please continue to pray for his friends and family. They appreciate your support."
Conaway has battled addictions to cocaine, alcohol and prescription painkillers since he was a teenager and talked about his struggles on the reality series in 2008. Conaway was also hospitalized in January 2010 after falling down a staircase in his home. He broke his hip and arm, fractured his back and suffered a brain hemorrhage.
Aside from "Grease" and "Taxi," Conaway appeared on the sci-fi series "Babylon 5" in the 1990s as Zack Allan. In recent years, he appeared in small film projects. Before his death, he was working on a thriller called "Human Factor," which features "Buffy The Vampire Slayer" actress Charisma Carpenter, Eric Roberts and Sean Patrick Flanery.
Conaway was married twice - first to Rona Newton-John, sister of the actor's "Grease" co-star Olivia Newton-John, between 1980 and 1985. He married his second wife, Kerri Young, in 1990. The two later separated. The actor has no children of his own.