CBS News reports that an air force base psychologist has been accused of sexual abuse and rape at the Travis Air Force Base in California. Dr. Heath Sommer has been arrested for multiple felony sexual assault and battery charges and is pleading not guilty to all of them.

The official complaint against the doctor was filed on Monday, outlining his methods of “exposure therapy,” which he used to inflict abuse on patients that they likely already suffered before seeking treatment. The alleged abuse happened between 2010 and 2016, but it is not known how many victims there were in total. Many of them were likely sexual abuse victims before ever seeing the doctor. His charges include sexual battery, rape and oral copulation.

Sommer was working on a contract basis at the base’s David Grant Medical Center, but is no longer working there. A spokesperson told media sources that the Air Force and Travis Air Force Base “have zero tolerance for sexual assault.”

Sommer is being held with a $750,000 bail in Fairfield at the Stanton Correctional Facility. This is just east of the base, which is 45 miles northeast of Sacramento. Travis Air Force Base has been in operation for 75 years.

*Photo credit CBS Sacramento