FAIRFIELD, Calif. (AP) — A psychiatrist hired by a U.S. Air Force base to help military veterans in California dealing with post-traumatic stress disorder has been charged with raping female service members who were in therapy for the crime he is now accused of committing — sexual assault.

Dr. Heath J. Sommer was ordered Monday to stand trial on three felony sexual assault charges after authorities said he targeted female service members in 2014 and 2015 while working at Travis Air Force Base's David Grant Medical Center, about 45 miles northeast of Sacramento, The Daily Republic in Fairfield, California reported .

Sommer was arrested earlier this month and pleaded not guilty to the charges.

A telephone message for his attorney, Thomas Maas, seeking comment was not immediately returned. He told the judge the sex was consensual. Maas said his client had not committed a crime and the actions were part of his therapy work.

Prosecutors allege the 41-year-old psychiatrist used a technique called exposure therapy and moved the sessions to his home where he asked the women to have sex with him, leaving them "even more traumatized."

One of the women, an officer in therapy after being raped in 2002 while deployed to Afghanistan, told the investigator that Sommer wanted to treat her by having her re-experience every facet of her sexual assault and then asked her to have sex with him so she could have a "positive and loving" experience, according to court documents.

Another woman told the investigator that as part of Sommer's "exposure therapy" in 2015, he exposed himself and had her give him oral sex in his office. In another session, he groped her, according to the criminal complaint.

Sommer also faces four charges of sexual battery filed after his 2016 arrest by Fairfield police, according to the newspaper. He remains in jail with bail set at $750,000.