Lisa Robin Kelly Lisa Robin Kelly

An autopsy has been completed on former That '70s Show star Lisa Robin Kelly, but her cause of death probably won't be known for another couple of months, CNN reports.

It will take eight to 10 weeks to get toxicology results back for the actress, who died at a rehab facility last week at age 43.

Fall TV Preview: Where we left off with returning shows

Kelly had voluntarily checked herself into the facility to seek treatment for addiction issues. She passed away in her sleep Wednesday evening.

The actress is best known for playing Laurie Forman, the older sister of Eric Forman (Topher Grace) on That '70s Show.