E! News has learned that although the autopsy examination is complete, the Deputy Medical Examiner has "deferred" the That '70s Show star's final cause of death pending results of additional tests and tissue studies.
According to the Los Angeles Coroner's office, "We are probably looking at approximately 6-8 weeks before the case will be closed. In the interim, we are unable to comment further until all of the results have been received and the case officially closed by the Coroner."
The actress died last week after a long battle with addiction. She was 43.
"Unfortunately Lisa Robin Kelly passed away last evening," her agent told E! News. "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. I spoke to her on Monday and she was hopeful and confident, looking forward to putting this part of her life behind her. Last night she lost the battle."
Kelly is best known for her role as Laurie Forman, the floozy older sister to Eric Forman—who was played by Topher Grace—on the hit Fox sitcom.
—Reporting by Marcus Mulick