Joan Rivers' personal throat doctor, Dr. Gwen Korovin, reportedly never performed an "unauthorized procedure" on the comedian that put her into cardiac arrest, which later resulted in her death on September 4.

According to a source close to Korovin, Rivers underwent three procedures before her vocal cords swelled and cut off her oxygen supply -- two by Korovin and one by Yorkville Endoscopy clinic's former medical director Dr. Lawrence Cohen, a gastroenterologist who allegedly resigned from practicing at the Manhattan clinic following the event of River's sudden death, CNN reported.

Korovin reportedly first executed a laryngoscopy enabling her to view Rivers' vocal folds. Afterwards, Cohen performed an endoscopy intended to diagnose why she was suffering a sore throat and hoarseness, according to CNN.

Once Cohen found something wrong, the source explained Korovin initiated a second laryngoscopy to take another look at the vocal cords, which started to swell. Korovin was reportedly authorized only to observe Cohen at work, as she wasn't certified by Yorkville Endoscopy clinic, as required by New York health law.

Yorkville Endoscopy has firmly denied Rivers ever having received a vocal cord biopsy, which would appear to be consistent with the new CNN source.

Investigators, however, have allegedly failed to find a prior consent form signed by Rivers, allowing Korovin to perform any type of procedure.

Korovin also "categorically denies" taking a selfie photo while Rivers was under anesthesia at the clinic, according to the source. Staff at the clinic had told CNN they heard Korovin say something along the lines of, "[Rivers] will think this is funny" or "would love this" as she took the selfie.

Rivers, 81, died one week after suffering cardiac arrest at Yorkville Endoscopy clinic.

Korovin's lawyer sent a statement to CNN on Thursday in response to reports of a selfie photo and unauthorized biopsy.

"Gwen S. Korovin, M.D. is a highly experienced, board certified otolaryngologist.  She maintains privileges at one of the city's most prestigious hospitals. She is respected and admired by her peers in the medical community and she is revered by her patients," the lawyer said.

"As a matter of personal and professional policy, Dr. Korovin does not publicly discuss her patients or their care and treatment. Further, Dr. Korovin is prohibited by state and federal confidentiality laws from discussing her care and treatment of any particular patient."

Added Korovin's lawyer, "For these reasons, neither Dr. Korovin nor her attorneys will have any public comment on recent press reports regarding her practice. We ask that the press please respect Dr. Korovin's personal and professional policy of not discussing her patients, as well as the privacy of her patients."