(JTA) — Joan Rivers died from lack of oxygen during surgery, the New York City medical examiner’s office said.

The comic’s death “resulted from a predictable complication of medical therapy,” the medical examiner said in findings released late last week.

”In response to NYC’s medical examiner’s report, we continue to be saddened by our tragic loss,” Rivers’ daughter, Melissa, posted on Twitter. “No further comment at this time.”

Rivers died Sept. 4 while undergoing a laryngoscopy, a routine procedure in which a doctor examines the back of the throat and vocal cords, in a New York clinic. She had been complaining of recent changes to her voice, according to the Hollywood Reporter. Rivers went into cardiac arrest during the procedure.

No autopsy was performed, TMZ reported, at the request of Melissa at the time of her mother’s death.

Rivers was sedated with propofol, the drug that was implicated in the death of Michael Jackson, though it is has not been connected to Rivers’ death.

The New York State Department of Health also is investigating the death.