Comedian and actor Robin Williams, 63, died from "asphyxia due to hanging," according to preliminary findings announced at a press conference on Tuesday by Lt. Keith Boyd of the Marin County's Sheriff's Office.

Williams was discovered on Monday shortly before noon by his personal assistant who became concerned when the actor did not respond to several knocks on the door, Boyd said. Williams’ wife, Susan Schneider, last saw her husband alive around 10:30 p.m. when she went to bed.

Schneider left the home around 10:30 a.m. Monday, assuming Williams was still asleep, Boyd said. Williams had retired to a different room and was found fully clothed with a belt tied around his neck. The belt was wedged between the closet door and door frame, and Williams "was in a seated position slightly suspended off the ground," Boyd said. "What that means is that his body looked like he was sitting in a chair."

Schneider returned to the home after Williams had been declared deceased by police and the Fire Department, Boyd said. Boyd would not say if Williams left a note. The actor also had superficial stab wounds on his left wrist and a pocket knife was found next to his body, Boyd said.

Toxicology tests will be conducted, and the investigation will continue to determine an approximate time of death, Boyd said. Rigor mortis had set in when Williams' assistant found him, he said..

The Oscar-winning legend battled addiction for decades and recently was suffering from "severe depression," his publicist said.

A father of three, Williams recently posted on Instagram a photograph of him and his daughter, Zelda, on her 25th birthday. In April, he posted a black and white photograph of his son Zak on his 31st birthday. He also had a 22-year-old son, Cody.