( PEOPLE.com ) -- Cameron Douglas , who is serving a five- year federal prison sentence for drug dealing , pleaded guilty Thursday to possessing drugs in his jail cell . For the latest charges , the son of actor Michael Douglas faces a maximum sentence of 20 years in prison , followed by three years of supervised release , plus a $ 250,000 fine . Douglas , 32 , is charged with possessing items that tested positive for cocaine and heroin , which were found in his cell by an investigator . Assistant U.S. Attorney Justin Anderson told the court one of the substances tested positive for methadone , which he described as `` something that people take when they 're coming off a heroin addiction in order to facilitate the withdrawal , '' according to a court transcript . The charges state that Douglas obtained the narcotics both at the Metropolitan Correctional Center in Manhattan , as well as after he was transferred to a minimum-security jail in Lewisburg , Pennsylvania In court Thursday , he admitted struggling with addictions to heroin , cocaine and alcohol . `` God knows I am sorry , '' records show he told the judge . Michael Douglas said in a statement : `` Cameron accepts full responsibility for his conduct , which involved a small user-quantity of drugs . While he has made much progress , he is still not cured . Most people and their families are able to address this illness privately and outside of the spotlight . Unfortunately this has not been possible here , for reasons completely outside of his control . He thanks those that have rooted for his recovery and looks forward to the day when he will not disappoint . '' Douglas is scheduled to be sentenced December 21 . See the full article at PEOPLE.com . © 2011 People and Time Inc. All rights reserved .
Cameron Douglas faces a maximum sentence of 20 years in prison . The former British soldier was found guilty last month on two counts of murder and one count of attempted murder. `` God knows I am sorry , '' he says .