The Los Angeles County coroner's office has performed an autopsy on Saturday to determine what killed actor Jeff Conaway who passed away at age 60, authorities said.

However, the findings were not expected soon as it could take six to eight weeks for toxicology tests to produce results, according to officials from the coroner's office.

Jeff Conaway, best known for his roles in the 70s' hit television series "Taxi" and blockbuster film "Grease," died at an Encino hospital in southern California Friday morning.

The former child star began acting on Broadway when he was only two years old. His family took him off life support on Thursday night.

Conaway was hospitalized earlier this month after being found unconscious at an Encino Apartment by his girlfriend Vikki Lizzi on May 11 due to a reported drug overdose.

"Celebrity Rehab" host Drew Pinsky, who treated Conaway on the show in 2008, tweeted that Conaway had not overdosed, but was suffering from a combination of pneumonia and sepsis. Conaway had been placed in a medically induced coma, according to Pinsky. The actor never recovered from his coma and was pronounced dead on Friday.

Conaway's condition was inevitable because he had been a serious pill popper for years and the constant substance abuse wore down his body, Pinsky said, according to celebrity web portal TMZ.com.

His career was plagued with substance abuse problems since the mid 1980s. The actor suffered a back injury while filming "Grease," which led to an addiction to painkillers.

On VH1's reality series "Celebrity Rehab," he admitted addictions to cocaine, alcohol and painkillers, making viewers shocked. He appeared on the second series of the show and was often seen in a wheelchair as his condition and addictions seemed to worsen.

Conaway suffered a near fatal fall that caused a brain hemorrhage and neck and hip fractures that he struggled to recover from in 2010.