It was revealed following his death that Williams had been suffering from severe depression, and had been sleeping in a different room from his wife due to restlessness and anxiety caused by his Parkinson's.
The final autopsy report, released in November 2014, affirmed that Williams had committed suicide as initially described; neither alcohol nor illegal drugs were involved, while any prescription drugs present in Williams' body were at "therapeutic" levels. The report also noted that Williams had been suffering "a recent increase in paranoia". An examination of his brain tissue revealed the presence of "diffuse Lewy body dementia". Williams' doctors reportedly believe that Lewy body dementia "was the critical factor" that led to his suicide.