Los Angeles ( CNN ) -- Why actress Lisa Robin Kelly died in an addiction rehab center last week will not be known for another two months , a coroner 's office spokeswoman said Sunday . The autopsy on Kelly , one of the stars of TV 's `` That '70s Show , '' was completed Saturday , but it will be another eight to 10 weeks before toxicology results are back from the lab , according to Los Angeles County Coroner Lt. Cheryl MacWillie . `` Lisa had voluntarily checked herself into a treatment facility early this week where she was battling the addiction problems that have plagued her these past few years , '' agent Craig Wyckoff told CNN on Thursday . `` I spoke to her on Monday and she was hopeful and confident , looking forward to putting this part of her life behind her . '' She died late Wednesday in a Los Angeles area treatment facility , he said . Kelly , 43 , played Laurie Forman -- older sister of Eric Forman , played by actor Topher Grace -- on `` That '70s Show , '' which ran from 1998 to 2006 . People we 've lost in 2013 .
The autopsy on Kelly was on Saturday . ` ` Addiction problems '' plagued Kelly ` ` these past few years , '' he said . Kelly died late , in a Los Angeles area treatment facility . Kelly met Laurie Forman on ` ` That ' 70s Show ''