A San Francisco police officer was arrested on charges of sexual assault Monday, officials said.

Justin McCall, 30, of San Francisco, was booked into San Francisco County Jail on charges of sexual assault when the victim is prevented from resisting by an intoxicating substance and sexual assault of a victim who was unconscious or asleep, San Francisco police officials said.

The San Francisco Police Department’s internal affairs criminal division was notified of the allegation in September of 2017 and opened an investigation, officials said.

McCall, who was off duty at the time of the alleged assault, was removed from direct contact with the public and reassigned from his role in the Field Operations Bureau.

“The public’s trust is of the utmost importance to the members of the SFPD and the department will continue to work hard to build and maintain this trust,” the department said in a statement. “As San Francisco Police Chief William Scott has stated, department members will continue to hold each other accountable and will act swiftly to report any behavior that might bring dishonor to the police department and the city of San Francisco.”

McCall, a four-year veteran of the department, has been suspended without pay following his arrest.

Annie Ma is a San Francisco Chronicle staff writer. Email: ama@sfchronicle.com Twitter: @anniema15