AceShowbiz -

Actress Lisa Robin Kelly's autopsy was completed last Saturday, August 17. The cause of death, however, is still unknown and won't be revealed until after at least two more months needed to get the toxicology results back from the lab, according to the Los Angeles coroner's office.

Kelly died in her sleep on Wednesday, August 14 within days after she voluntarily checked herself into a California rehab facility earlier in the week to get treatment for her alcohol addiction, something that has hounded her for the past few years. She was only 43 years old at the time of her passing.

Best known for her role as Laurie Forman, elder sister of the character played by Topher Grace on the now defunct Fox period sitcom "That '70s Show", Kelly made her TV debut with the same network in the long-running sitcom "Married... with Children". In recent years, she had been arrested for varying offenses as driving under the influence, spousal abuse and assault.

Kelly's death remains a mystery, since no drugs or alcohol were found in her room despite her history of alcohol and substance abuse. There were also no signs of foul play according to authorities.

Her agent Craig Wyckoff recounted having spoken to Kelly just days before her death, "I spoke to her on Monday, and she was hopeful and confident, looking forward to putting this part of her life behind her." Sadly, she "lost the battle" with addiction to alcohol, compounded by substance abuse that got started when she took prescription drugs after she got injured on the set.