As the investigation into the death of Joan Rivers continues, new details are emerging about the doctor at the center of the probe.
Sources have identified Gwen Korovin, a doctor to the stars who served as Rivers's personal physician, as the one who performed an unauthorized vocal cord biopsy on the comedian. The biopsy was reportedly performed following the routine endoscopy for which Rivers had initially gone into the Yorkville Endoscopy clinic.
Korovin has been linked to clientele including Lady Gaga, Hugh Jackman, John Mayer, Daniel Radcliffe, Sean Hayes, Brooke Shields, and Patti LuPone. She recently appeared in a documentary where she was seen examining Celine Dion.
TMZ reported Wednesday that Dr. Korovin was not authorized to be present at Yorkville Endoscopy the day of Rivers's procedure. CNN reported on Tuesday that Korovin took a selfie while Rivers was under anesthesia for the unscheduled biopsy. (No image has yet surfaced anywhere on social media sites.)
"Investigators believe that Rivers's vocal cords began to swell during the allegedly unauthorized biopsy, cutting off the flow of oxygen to her lungs, which led to cardiac arrest on the morning of Aug. 29," a source told CNN.
Rivers was placed in a medically induced coma and eventually died Sept. 4 at age 81 after being taken off life support.
TV host Wendy Williams, who told her audience on Wednesday that Korovin has also treated her, revealed to The Insider With Yahoo that Korovin is currently in hiding.
Williams also suggested that "maybe [Korovin] took the selfie because she thinks it's something that would have made Joan laugh."
Sources close to Korovin told TMZ on Thursday that the doctor claims CNN's source is lying and that she neither performed a biopsy on Joan, nor took a selfie while Joan was under anesthesia.
Both the New York Police Department and the New York State Department of Health are looking into the circumstances surrounding Rivers's death, but neither has issued a formal comment about the status of their investigations.
Meanwhile, Yorkville Endoscopy's gastroenterologist and medical director, Dr. Lawrence Cohen, who performed Joan's scheduled endoscopy, stepped down from his post last Friday.
Citing privacy laws, the clinic has refused to comment beyond asserting that no vocal cord biopsies have ever been performed at the facility.
[Related: Investigations, Memorials, Controversy: The Latest on Joan Rivers]
In other Rivers-related news, the New York Daily News, citing a source close to the family, reported Thursday that Joan's $150 million estate would be left to daughter Melissa, grandson Cooper, and Joan's beloved quartet of rescue dogs.
The probate has yet to be formally filed in court, however. The firm of Loeb & Loeb is currently handling the paperwork, according to The Insider.
While her estate and the circumstances of Joan's death remain unsettled, there are several tributes in the works.
Leslie Bennetts, a journalist for Vanity Fair and The New York Times, will be writing a biography, Joan Rivers: A Life, described as "the definitive book about Rivers's tumultuous, victorious, tragic, glamorous, and fascinating life."
W magazine unveiled plans to give Joan the royal treatment by profiling her in its October issue, including a glamorous portrait that was the last styled photo she ever posed for.
PBS's American Masters announced it would air the 2010 documentary Joan Rivers: A Piece of Work on Sept. 23 at 10:30 p.m. This broadcast will mark the PBS premiere of the film, which subsequently be streaming for a limited time on the American Masters website.
Meanwhile, E! — Joan's longtime home on cable television — will celebrate her with a full day of programming on Friday. Billed as "Joan Day," the block of shows will feature a marathon of her Fashion Police episodes from 7 a.m. to 7 p.m. ET/PT, capped by the 90-minute Fashion Police: Celebrating Joan tribute at 8 p.m. The 90-minute remembrance will be hosted by Fashion Police co-stars Kelly Osbourne, Giuliana Rancic, and George Kotsiopoulos, as well as Melissa Rivers in what will be her first public appearance since her mom's death.