SANTA ANA, Calif. (KTLA) -- An anesthesiologist in Orange County, already accused of sexually assaulting two female patients while they were unconscious, has now been charged with assaulting a third woman.

Yashwant Balgiri Giri, 58, is charged with one felony count each of sexual penetration by foreign object and sexual battery on a an institutionalized victim. On Monday, Giri pleaded not guilty to the charges.

A third victim came forward last week. Detectives say she was embarrassed about the incident, and only came forward after a psychologist encouraged her to tell the police.

The alleged victim told authorities she was assaulted at Placentia-Linda Hospital when she went in for a surgical procedure in April of last year. Before she was taken into the operating room, she was alone with Giri in another room. She told detectives Giri fondled her breasts and penetrated her with his fingers.

In May, Giri was charged with using his fingers to sexually assault a16- year-old girl under anesthesia during a knee operation in January 2009, Loomis said. He was also charged with fondling the breasts.

Giri is an anesthesiologist at the Placentia-Linda Hospital, but has worked at other hospitals in Southern California including Lakewood Regional Medical Center, Anaheim Regional Medical Center, West Anaheim Medical Center, and Western Medical Center, Anaheim.

Between Jan. 1, 2009, and Dec. 31, 2009, Giri is accused of administering anesthesia to 16-year-old Jane Doe #2 while she was unconscious from medication.

He is accused of digitally penetrating the victim while a scrub nurse was preparing the surgery tools with her back turned.

The nurse witnessed the sexual assault and immediately reported the incident to a director at the Placentia-Linda Hospital.

The hospital failed to report the incident to police at that time.

On March 18, 2011, Giri is accused of fondling the breasts of 36-year-old Jane Doe #1 while she was unconscious under anesthesia during an outpatient surgery procedure.

A hospital employee witnessed Giri fondling the victim's breast continuously while the procedure was taking place.

The hospital employee reported the sexual assault to a hospital director and police were contacted.

Giri is being held on $100,000 bail.

If convicted, he faces a maximum sentence of eight years in state prison.

Due to the defendant's work history, prosecutors fear their may be other victims.

Anyone with additional information or who thinks they have been a victim is encouraged to contact Supervising District Attorney Investigator Lou Gutierrez at (714) 347-8794.