( CNN ) -- The death of actor and comedian Robin Williams has officially been ruled a suicide , the coroner in Marin County , California , said Friday . Alcohol and illegal drugs were not involved , the statement from the coroner 's office said . Prescription drugs were found in `` therapeutic concentrations , '' the statement added . Williams was found dead in his Tiburon , California , home August 11 from what investigators suspected was a suicide by hanging . He was 63 years old . The death certificate , obtained by CNN on August 21 , says his ashes were scattered off the coast one day later . Investigators believe Williams used a belt to hang himself from a bedroom door , Marin County Assistant Deputy Chief Coroner Lt. Keith Boyd said at the time . Williams was sober but struggling with depression , anxiety and the early stages of Parkinson 's disease when he died , his widow , Susan Schneider , said in a statement in August . `` Robin spent so much of his life helping others , '' she said . Whether he was entertaining millions on stage , film or television , our troops on the front lines , or comforting a sick child -- Robin wanted us to laugh and to feel less afraid . '' Williams had `` a recent increase in paranoia '' and was sleeping in a stepson 's bedroom because of insomnia and anxiety associated with Parkinson 's , according to the coroner 's report . A pathology report released Friday said Williams was diagnosed with Parkinson 's disease in November 2013 , several years after he first noticed symptoms such as tremors in his left arm and a slowing of his left-hand movements . Last call made to wife . The coroner 's report said his body was found about 11:45 a.m. by a personal assistant , who used a paperclip to open the locked door of the bedroom where Williams had been sleeping . Williams was found in a seated position on the floor of the bedroom with a belt secured around his neck and the other end of the belt wedged between a closet door and door frame . The actor was wearing black jeans and a black short-sleeve T-shirt , the coroner 's report said . A cellphone recovered from Williams ' pants pocket was dead . After recharging the phone , the coroner searched through its texts and emails and found no messages referencing suicide , the report said . The last call on the phone was made the night before to Williams ' wife , Susan , and lasted 38 seconds . In one incident the evening before he died , Williams took several wristwatches and put them into a sock and took them to someone 's house for safekeeping , an indication of his paranoia , his wife suggested . Also noteworthy , according to Williams ' wife , is that he may have learned of the suicide technique from a movie role in which a character Williams portrayed died from autoerotic asphyxiation . Grief and remembrance . Williams ' death was met with an outpouring of grief and recollections . Friend Billy Crystal paid tribute to him at the Emmy Awards , and later helped Williams ' son , Zak , throw out the first pitch before Game 5 of the World Series while Williams ' other children watched . Daughter Zelda got a tattoo in honor of her father . Gilbert Gottfried , another friend , remembered a `` generous '' man who was welcoming to his fellow comedians . `` To see Robin perform was an experience . He was more than a comedian . He was a comedy force of nature , '' he wrote on CNN.com . Ellen DeGeneres , Jimmy Fallon , Conan O'Brien and David Letterman , among others , also paid tribute to the comedian . David Letterman pays tribute to Robin Williams . Oscar-winning performer . Williams ' long career was notable for his manic , improvisational comedy and his deeply felt acting performances . He won an Oscar for playing a therapist in the 1997 film `` Good Will Hunting . '' A number of his other films , including `` Mrs. Doubtfire '' and `` Patch Adams , '' were huge box-office hits . He was also active in a number of charitable causes and frequently took part in USO tours . Robin Williams : Full of demons , full of heart . On her Twitter feed , his daughter Zelda remembered her dad with a quote from Antoine De Saint-Exupery 's `` The Little Prince . '' `` In one of the stars I shall be living . In one of them I shall be laughing . And so it will be as if all the stars were laughing , when you look at the sky at night . ... You -- only you -- will have stars that can laugh . '' Complete coverage on Robin Williams . CNN 's Todd Leopold , Greg Botelho and Dan Simon contributed to this story .
Autopsy reveals no alcohol or illegal drugs in Robin Williams ' suicide . Actor and comedian died August 11 at age 63 . The actor was found dead of an apparent drug overdose on a bathroom floor by his housekeeper. Beloved performer was mourned deeply after death .