More details are emerging about Joan Rivers' death, and the latest report claims that the comedienne's personal doctor might have played a role in the disaster. On Thursday, Aug. 28, Rivers went to a New York City endoscopy center to have her vocal chords checked out.

According to the Daily News, Rivers arrived at the clinic with a group of people including her own doctor. Allegedly, the doctor offered to perform a surprise, unplanned biopsy on Rivers when another doctor noticed "something" on her vocal chords.

A medical source told the newspaper that Rivers' doctor then asked the clinic if he could borrow their instruments so he could perform the biopsy on the "Fashion Police" cohost. Reportedly something went wrong during the procedure that caused Rivers' vocal chords to seize, cutting off her air supply.

"A biopsy like that should only be done in a hospital setting," the source said. "If she had been in a hospital when it happened, she might have been OK."

While doctors tried to figure out what happened, Rivers' heart stopped beating.

"He asked, and they let him," the source said, referring to Rivers' doctor, who identified himself as an ear, nose and throat doctor. "A huge no-no."

According to the Daily News, the late comedienne signed off on the endoscopy but not the biopsy. It was previously reported that the New York State Health Department launched an investigation into the clinic, but it was strictly routine.

Last week, a spokesperson for the clinic told ABC News that Yorkville Endoscopy Center was fully cooperating with the investigation.

"Yorkville Endoscopy has performed 18,000 procedures since it opened in February 2013. Yorkville Endoscopy has maintained an exceptional safety record that far exceeds the national average," the spokesperson said.

Rivers never recovered from the procedure at Yorkville and died a week later, Sept. 4, at Mount Sinai Hospital. 

Update: Yorkville Endoscopy released a statement and denied that Rivers had a "biopsy on her vocal chords," the Daily News reports. The clinic also slammed reports that Rivers was under general anesthesia while she was there.

"General anesthesia has never been administered at Yorkville Endoscopy. The type of sedation used at Yorkville Endoscopy is monitored anesthesia care. Our anesthesiologists utilize light to moderate sedation," the statement read.