The Marin County sheriff’s office released the autopsy results Friday.
Williams had taken prescription medications, but they were found to be in “therapeutic concentrations”.
The coroner ruled his death a suicide that resulted from asphyxia due to hanging.
Sheriff’s officials have said Williams was found in the bedroom of his home on the morning of August 11.
His wife was sleeping in another room.
Sheriff’s Deputy Stewart Cowan said Friday that his office was not releasing further information from the report.
Williams’ wife, Susan Schneider, has said the actor and comedian was struggling with depression and anxiety and a recent Parkinson’s diagnosis when he was found dead by his personal assistant at his Marin County home.
Williams had publicly acknowledged his previous struggles with substance abuse, but was believed to have things under control.
He had entered a substance abuse rehabilitation program shortly before his death.
The results of Williams’ autopsy, including toxicology tests, were originally slated to be released September 20.
Marin County officials later announced a November 3 release date, but the report was further delayed. Toxicology reports routinely take up to six weeks to complete.
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