The actor Robin Williams tried to cut his wrist and hanged himself in a bedroom of his San Francisco Bay Area home after struggling with depression, officials said on Tuesday.
His wife, Susan Schneider, likely was home at the time but was unaware, Keith Boyd, a Marin County sheriff's lieutenant, said.
Williams was last seen alive by Schneider on Sunday night when she went to bed, Boyd said. She woke up the next morning and left, thinking he was still asleep elsewhere in the house.
Shortly after that, Williams' personal assistant came to the Tiburon home and became concerned when Williams failed to respond to knocks at a door. The assistant found the 63-year-old actor clothed and dead in a bedroom.
Boyd said all evidence indicated the star of dozens of films committed suicide.
But he said a final ruling would be made once toxicology reports and interviews with witnesses were complete.
The condition of the body indicated Williams had been dead for at least a few hours, Boyd said. Williams also had superficial cuts on his wrist, and a pocket knife was found nearby.
Williams' death led to an outpouring of grief among fellow actors, fans and politicians, with US President Barack Obama calling him "one of a kind".
The father of three had spoken openly of his past struggle with alcohol and substance abuse, and often made self-deprecating references to his addictions in his stand-up routines.
Williams won an Academy Award for Best Supporting Actor for his role in Good Will Hunting, and was known for his eccentric performances in movies including, Flubber, Good Morning Vietnam, and Jumanji.