Dr. Lawrence B. Cohen, the gastroenterologist who performed the throat procedure on Joan Rivers before she passed away, "is not currently performing procedures at Yorkville Endoscopy, nor is he currently serving as medical director," a spokesperson from the clinic said in a statement obtained by TheWrap.

It is unclear whether Cohen voluntarily stepped down or was axed from his post. But a source told ABC News that he was asked to step down because he allowed an unaffiliated ENT specialist to examine Rivers even though that doctor was not authorized to practice in the clinic.

A medical source told New York Daily News that the ENT specialist performed an unplanned biopsy on the "Fashion Police" host's vocal cords - a procedure that is not supposed to be performed outside of a hospital.

"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 okay,"

The ENT specialist reportedly asked if he could use the instruments when the clinic's doctor noticed "something" on the comedienne's vocal chords.

"He asked and they let him," the source added. "A huge no-no."

The said biopsy at Yorkville Endoscopy caused Rivers' vocal chords to seize (laryngospasm) cutting off her air supply, the source explained.

However, the clinic fired back at those allegations, saying in a statement that "a biopsy of the vocal cords has never been performed at Yorkville Endoscopy."

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

According to New York state records, Cohen is a co-owner of Yorkville Endoscopy. There are also no disciplinary actions on his record and his license is current.

He has also taught at the Mount Sinai School of Medicine, contributed over 150 books and articles about gastroenterology and lectured around the world on subjects ranging from colonoscopy and colorectal cancer screening to endoscopic sedation, according to a biography posted on the clinic's website.

A Mount Sinai spokesman said Cohen no longer teaches there, but still has a professional relationship with the hospital, The Seattle Times reported.

"Dr. Lawrence Cohen is a voluntary physician with admitting privileges at The Mount Sinai Hospital," spokesman Sid Disnay said. "He maintains a private practice."