An autopsy has been completed on late That 70's Show star Lisa Robin Kelly after she suddenly passed away in her sleep late this past Wednesday, but, according to TMZ, the cause of death is reportedly still unknown.

A spokesperson for the L.A. County Coroner's Office revealed the news: The autopsy was inconclusive, meaning that Kelly's cause of death won't be known until her toxicology results come back—which will likely take weeks. 

As previously reported, Kelly passed away while in a rehab facility in LA for alcohol addiction. She was admitted just a couple of days prior, after her boyfriend took her to a hospital where her blood alcohol level was recorded at .34—nearly lethal. Kelly had battled drug and alcohol problems for years after leaving her role as Laurie Foreman on That 70's Show in 2003, and was arrested numerous times for assault and drug charges.

Kelly was 43 at the time of her death.

[via TMZ]