The preliminary investigation into the death of Robin Williams found that the Oscar-winning actor and comedian hung himself with a belt in a bedroom of his Northern California home, the Marin County sheriff's department has said. Keith Boyd told a press conference Tuesday that the case remained open and it would take several weeks before the official cause of death could be known. Williams' lifeless body was found shortly before noon Monday by his assistant, who - after knocking at his bedroom door and getting no response - became concerned and decided to enter the room in Tiburon, near San Francisco. According to Boyd, the 63-year-old Williams was "clothed in a seated position, unresponsive, and with a belt secured around his neck with the other end of the belt wedged between the closet door and door frame". Boyd also said that Williams has small and superficial cuts on the inside of his left wrist and investigators found a pocketknife near the actor's body, on the blade of which was a dry, red substance "consistent with dried blood". Medical examiner Joseph Cohen said that there were no signs of any physical altercation before Williams died. Toxicology tests to determine if the actor was under the influence of drugs or alcohol before dying are still pending and the results will not be known for four to six weeks. (Source: IANS)