The Los Angeles County Coroner has declared Grease star Jeff Conaway's death an accident after a four month investigation into the tragedy.

The actor died a day after he was taken off life support in May. He was 60.

Conaway was hospitalized at Encino Hospital Medical Center after he was found unconscious at his home in California.

The actor's spokesman Phil Brock revealed he was found with a cocktail of "painkillers and cold medicine in his system", and doctors went on to diagnose him with pneumonia and sepsis, a potentially fatal blood poisoning caused by a bacterial infection.

He remained in a coma and his family decided to switch off his life support machine after being told he was unlikely to ever regain consciousness.

And now the autopsy results are complete - Conaway, who is best known for playing Kenickie in Grease, died from multiple causes, including Aortic Valve Endocarditis, Coronary Artery Disease and a brain disorder resulting from past drug overdoses, reports TMZ.com.