An initial autopsy into Joan Rivers' exact cause of death has proved inconclusive.
The veteran comedienne passed away at New York's Mount Sinai Hospital on Thursday, a week after suffering a cardiac and respiratory arrest during a routine throat operation at a nearby clinic.
A representative at the Medical Examiner's Office tells TMZ.com coroners completed a physical examination of the 81-year-old's body on Friday, but could not find a clear "cause and manner of death".
Toxicology tests are now underway, but results are not expected to be available for several weeks.
Officials at the Medical Examiner's Office will also interview the doctors and nurses who were present during Rivers' throat procedure at Yorkville Endoscopy in a bid to determine what went wrong.
Authorities at the New York State Health Department have also launched a review into the clinic, where bosses have been forced to step up security after staff were bombarded with death threats following Rivers' death.Copyright WENN.com