Robin Williams suicide: Actor had no illegal drugs or alcohol in his system when he died, autopsy results show

Police officially ruled his death a suicide with the release of autopsy results

Touching lives: Robin Williams in 2011 (AP)

Robin Williams’s death has been officially ruled a suicide by officials who found no illegal drugs or alcohol in the actor’s system.

The Marin County sheriff's office ruled that the cause of his death, on 11 August, was asphyxia due to hanging.

Autopsy results revealed today showed that Williams, 63, had taken prescription drugs but only in “therapeutic concentrations”.

The Oscar-winning actor was last seen alive by his wife, Susan Schneider, at home in Tiburon, northern California, on the previous evening.

He seemed "excited" and appeared to be well, she said, using an iPad for the first time after months of not watching television or reading.

She left the house at around 10.30am on Monday and when Williams's personal assistant arrived just over an hour later, she became worried when he failed to answer the door, police said.

Presenter Robin Williams speaks during the 35th Annual People's Choice Awards held at the Shrine Auditorium on January 7, 2009 in Los Angeles, California. (Getty)

When she managed to get into his room, she found him dead.

In a statement, Ms Schneider said: “I lost my husband and my best friend, while the world lost one of its most beloved artists and beautiful human beings. I am utterly heartbroken.

“It is our hope the focus will not be on Robin's death, but on the countless moments of joy and laughter he gave to millions.”

The sheriff's office said on Friday that no further information from the autopsy report would be released.

Ms Schneider had previously said the comedian was struggling with depression, anxiety and a recent Parkinson's diagnosis when died.

Williams had publicly acknowledged periodic struggles with substance abuse and entered a rehabilitation programme shortly before his death.

President Barack Obama was among the countless politicians, actors and celebrities sharing their memories of Williams after his death in an international outpouring of grief.

The President said: “He was one of a kind. He arrived in our lives as an alien - but he ended up touching every element of the human spirit. He made us laugh. He made us cry.”

Williams was married three times and had three children and he and Ms Schneider, a graphic designer, wed in October 2011.

He also left behind four complete performances in films yet to be released, including a reprise of his role as President Teddy Roosevelt in the third instalment of the Night at the Museum comedies.

He first achieved fame as eccentric extra-terrestrial Mork in the popular late-70s sitcom, Mork and Mindy and was nominated for an Academy Award three times - for his performances in Good Morning, Vietnam (1987), Dead Poets Society (1989) and The Fisher King (1991) - before he finally won the Oscar for Best Supporting Actor in Good Will Hunting(1997).

Additional reporting by agencies