Speaking to a bank of reporters on Tuesday, Lt. Keith Boyd said Williams' personal assistant found his body a day earlier seated in a chair near the closet door with a belt around his neck in his Tiburon home about 11:45 a.m.
Williams' left wrist also had several lacerations, Boyd said. A pocketknife was found in a bedroom nearby. There was what appeared to be blood on the knife, but Boyd said they haven't positively identified who it belonged to.
Boyd confirmed what Williams' publicist had stated on Monday. The iconic actor and comedian had "been seeking treatment for depression." He declined to say more, citing federal privacy laws.
In addition, Boyd stressed the findings by Marin County Chief Forensic Pathologist Joseph Cohen were preliminary, and he would not discuss whether the 63-year-old had left behind a message for anyone.
"We are not discussing the note, or a note, at this time," Boyd said.
Boyd also did not know if Williams had taken any drugs or alcohol before he committed "suicide by asphyxia." That information won't be known until a toxicology report is returned.
Boyd recounted a brief timeline of events that led to the shocking discovery.
Williams' wife, Susan Schneider, last saw her husband Sunday about 10:30 p.m. She retired to one room to go to sleep, and her husband went into another, Boyd said. That was the last time anyone saw him alive.
It wasn't until the next morning at 11:45 a.m., that Williams' personal assistant knocked on a bedroom door. There was no response, Boyd said. When the assistant went in, Williams' body was seated in a chair, and "cool to the touch." The "distraught" assistant called 911 at 11:55 a.m., Boyd said.
Boyd said it's unknown at this point exactly what time Williams killed himself, but the actor was pronounced dead on Monday at 12:02 p.m. when firefighters arrived.
It was well known that Williams had persistent battles with drug addiction, as he often made light of his cocaine use during his 1980s standup routines.
Williams returned to rehab last month. He said he had not relapsed, but was working on maintaining his sobriety.