Citing multiple sources, TMZ has identified Joan Rivers' personal doctor—the one accused of doing an unplanned biopsy and taking a selfie during Rivers' procedure—as Dr. Gwen Korovin, who boasts other celebrity patients, including Celine Dion and Lady Gaga. According to the gossip site, Korovin was the one working on Rivers when she stopped breathing, but the doctor was not authorized to practice medicine at the Yorkville Endoscopy center where the procedure took place. Since then, she's been keeping out of the spotlight. "Everyone close to Joan thinks Dr. Korovin skipped town," a source tells Radar. "Joan's daughter Melissa has been telling friends that she is a spineless monster." In other Rivers news: