Joan Rivers is believed to be killed by the same drug that killed legendary musician Michael Jackson after the authorities started investigating the clinic that performed surgery on late comedean.
According to Radar Online, the Fashion Police host was given the drug propofol proposal, which was often used as an anesthetic during surgery.
A source revealed that authorities suspected the anesthesia was the issue, based on conversations between the staff and city medics.
Meanwhile, Rivers' autopsy has not shown any clear cause of the death.
According to TMZ.com, the medical examiner's office asserted that they completed the autopsy but found no clear cause of death, and therefore, they will need more information with the help of further investigation.
The online publication also revealed that further investigation will include toxicology testing and interviewing medical professionals that took part in Rivers' surgery.