Award-winning actor and comedian Robin Williams has died at 63.

The cause of death is thought to be suicide by asphyxiation.

He was found unconscious in his home at about noon on Monday.

Williams had reportedly been battling depression, according to a statement from his press representative. In July, Williams checked into a rehab center in Minnesota to "fine-tune" his sobriety. 

Police are investigating the incident and the coroner will conduct toxicology testing this week before making a final determination on cause of death, according to a release from the Marin County Sheriff's Office.

Williams was last seen alive in the home that he shares with his wife at about 10 p.m. on Sunday.

Williams is known for his roles in "Good Will Hunting," "Mrs. Doubtfire," and "Hook." He won the Oscar for Best Supporting Actor for his work in "Hunting."

Williams had reportedly been working on a sequel to the popular "Mrs. Doubtfire" film.

His wife, Susan Schneider, released this statement:

This morning, I lost my husband and my best friend, while the world lost one of its most beloved artists and beautiful human beings. I am utterly heartbroken. On behalf of Robin's family, we are asking for privacy during our time of profound grief. As he is remembered, it is our hope the focus will not be on Robin's death, but on the countless moments of joy and laughter he gave to millions.

Williams' press representative Mara Buxbaum released this statement:

Robin Williams passed away this morning. He has been battling severe depression of late.

This is a tragic and sudden loss. The family respectfully asks for their privacy as they grieve during this very difficult time.

Williams has been fairly open about his battles with alcohol and drugs. He got sober before the birth of his first son in 1983.