A former massage therapist was convicted Monday of sexually assaulting a client, court officials said.

William Charles Stringfellow, 35, was found guilty of aggravated sexual battery in connection with the December 2010 incident, according to a news release from Fulton County District Attorney Paul Howard's office .

The 21-year-old woman was given the massage at a southwest Atlanta spa as a birthday gift from a friend, the release said.

Prosecutors said Stringfellow was assigned as the woman's massage therapist, and began touching her inappropriately shortly after the massage began.

Stringfellow fondled the woman and forcibly performed sex acts on the her even though she repeatedly told him to "stop," prosecutors said.

The victim left the business and called police from a hospital where she was being examined after the assault, authorities said.

Stringfellow was arrested following an extensive investigation and he remains in the Fulton County Jail.

Stringfellow is scheduled to be sentenced on Thursday and faces a mandatory minimum sentence of 25 years.