Los Angeles County Coroner Lt. Cheryl MacWillie told the outlet that Kelly's autopsy was completed on Saturday, but toxicology results will not be available for another eight to 10 weeks.
The former "That '70s Show" star died Wednesday, Aug. 14 in her sleep at a rehabilitation facility in California. She was 43 years old.
TMZ previously reported law enforcement called Kelly's cause of death "a mystery." There were allegedly no drugs in her room and no signs of trauma.
Earlier last week, Kelly voluntarily checked herself into rehab to deal with "the addiction problems that have plagued her these past few years," her agent told People magazine.
"I spoke to her on Monday, and she was hopeful and confident, looking forward to putting this part of her life behind her," Craig Wyckoff said.
The actress has had several legal issues in recent years. In June, she was arrested on suspicion of driving under the influence after her car stalled on a freeway in Burbank, Calif., the Los Angeles Times noted.