The Marin County Sheriff’s Department in a news conference today disclosed that Robin Williams' death Monday came from an apparent hanging in his Tiburon, Calif., home.

The preliminary investigation determined the 63-year-old actor died on Monday morning from asphyxia due to hanging.

“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 the door frame,” Lt. Keith Boyd said at the news conference.

There were also “acute superficial transverse cuts” on his inner left wrist, as well as chemical substances found in his system.

Further test results will be available in two to six weeks, authorities said.

Williams’ personal assistant found his body in his bedroom Monday. The assistant gained access to his bedroom about 11:45 a.m. PDT after becoming concerned when there was no response to multiple knocks on the door.

The Academy Award winner’s wife, Susan Schneider, was the last to see her husband alive, E! reported. She went to sleep about 10:30 p.m. Sunday, left the house Monday morning and returned after his body had been discovered.

Police said the investigation is still ongoing.