Doctor behind Joan Rivers' procedure asked to step down from Yorkville Endoscopy

NEW YORK (KABC) -- Yorkville Endoscopy has asked the doctor who performed Joan Rivers' endoscopy to step down, a source told ABC News on Friday.

Dr. Lawrence Cohen, a gastroenterologist, was the clinic's medical director. New York state records also listed Cohen as co-owner of the clinic.

In a statement to ABC News, Yorkville Endoscopy said Cohen "is not currently performing procedures," but did not say why.

But according to ABC News' source, Cohen allowed a specialist who was not authorized to practice at Yorkville Endoscopy to examine Rivers.

"HIPPA laws prevent us from disclosing any information about patients," a clinic representative said.

The New York State Health Department launched an investigation into the clinic about a week ago. The city medical examiner is also investigating.

Cohen is known to be a respected doctor. He has taught at the Mount Sinai School of Medicine, contributed to more than 150 books and articles on gastroenterology and lectured on various topics, including endoscopic sedation, according to a biography posted on the clinic's website.

There are no disciplinary actions on Cohen's record and his license is current, according to state records.

Rivers died Sept. 4 at Mount Sinai Hospital, a week after going into cardiac arrest. Close friend Deborah Norville said Rivers underwent a procedure to "see why her voice had gotten raspy."

ABC News and the Associated Press contributed to this report.