Comedy legend Joan Rivers passed away Sep. 4 at the age of 81, and now a New York medical examiner is attributing her death to a “therapeutic complication.” The examiner stated Thursday that this complication resulted in a loss of oxygen, when led to brain damage and the icon’s death.

According to the medical examiner, Rivers had been sedated with propofol and was undergoing a procedure at the Yorkville Endoscopy Center to evaluate changes in her voice and a digestive disorder. While sedated, a complication occurred which stopped the comedian’s breathing, and the resulting lack of oxygen killed her.

“The cause of Ms Rivers’ death is anoxic encephalopathy due to hypoxic arrest during laryngoscopy and upper gastrointestinal endoscopy with propofol sedation for evaluation of voice changes and gastroesophageal reflux disease,” stated the examiner. “The death resulted from a predictable complication of medical therapy.”

“She stopped breathing and her heart went into arrhythmia because there wasn’t sufficient oxygen to maintain the heart muscle,”  pathologist and surgeon Bill Lloyd, who was not involved in Rivers’ autopsy, explained to CNN. “The pump, the heart itself, was unable to move fresh oxygenated blood upstream to the brain.”

The New York State Health Department launched an investigation into her death in September, and has not yet stated whether or not these findings are enough to close the investigation.

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