Robin Williams' cause of death was revealed during a press conference today by the Marin County Sheriff's Department.

The Oscar winner died from asphyxia due to hanging Monday morning and was found by his personal assistant slightly suspended in a seated position.

Chemical substances were found in his system at the time of his passing, and toxicology results will not be made available for approximately two to six weeks while testing is being performed.

Marin County Sheriff's Lt. Keith Boyd told reporters that Williams had hanged himself with a belt and had cut himself with a pocket knife.

"Mr. Williams [was found] clothed in a seated position, unresponsive, and with a belt secured around his neck with the other end of the belt wedged between the closed closet door and door frame," Boyd told reporters.