Robin Williams found dead in California | PHOTOS, REACTION

His wife Susan Schneider released a statement asking for privacy for her family "during our time of profound grief".

"This morning I lost my husband and my best friend while the world lost one of its most beloved arists and beautiful human beings," she said. "I am utterly heartbroken."

"As he is remembered, 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."

Williams' publicist released a statement saying the actor had suffered severe depression lately.

"This is a tragic and sudden loss," the publicist said. 

A statement on the Marin County Sheriff's department website said officers responded to a 911 call about 11.55am on Monday morning (US time). 

The call indicated a man was found unconscious and not breathing in his home in Tiburon, California.

Emergency services arrived about midday, pronouncing 63-year-old Robin Williams dead a few minutes later.

"An investigation into the cause, manner, and circumstances of the death is currently underway by the Investigations and Coroner Divisions of the Sheriff’s Office," the statement said.

"At this time, the Sheriff’s Office Coroner Division suspects the death to be a suicide due to asphyxia, but a comprehensive investigation must be completed before a final determination is made."

Marin County Sheriff's Department said Mr Williams was last seen alive at his property, where he lives with his wife, about 10pm the night before. 

Toxicology tests will also be carried out, the sheriff's statement said. 

Support is available for those who may be distressed by phoning Lifeline 13 11 14; Mensline 1300 789 978; Kids Helpline 1800 551 800.

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