FAIRFIELD (AP) — A clinical psychologist hired by a U.S. Air Force base in California to treat military veterans 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, officials said Tuesday.

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 (72 kilometers) northeast of Sacramento.

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

His attorney, Thomas Maas, did not return telephone messages seeking comment. Maas told the judge at a hearing Monday in Fairfield, California, that the sex was consensual, according to The Daily Republic newspaper. Maas said his client had not committed a crime and the actions were part of his therapy work.

Prosecutors allege the 41-year-old psychologist used a technique called exposure therapy and would ask 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 moved the sessions to his home.

He told her he 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 the prosecution.

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 testimony at the hearing reported by the newspaper.

The base hired Sommer through a contracting company in 2014 and he treated more than 100 people before being suspended on July 12, 2016, said Staff Sgt. Amber Carter, a base spokeswoman.

He was vetted by the contracting company, Aloha Health Joint Venture, and the Air Force also did a background check, Air Force officials said.

“Nothing popped up during the background check,” said Tonya Racasner, a base spokeswoman.

As soon as Air Force officials learned of the allegations, they took immediate action and suspended him, she added.

“We take sexual assault very seriously,” Racasner said.

In light of the case, she said the base is looking at its procedures and also reviewing the treatments given at its medical center, she said, adding that exposure therapy usually entails writing a narrative about one’s experience.

“We don’t really condone exposure therapy,” she said.

The base also reached out to all of Sommer’s patients to offer help, she said.

The case comes as sexual assault continues to be a pervasive problem in the military.

According to an annual Pentagon report released in April, the number of reported sexual assaults grew by about 10 percent, while sexual harassment cases were up by 16 percent over the previous year.

Pentagon officials say the increase in reporting reflects a broader confidence in the system and is a positive trend because sexual assault is a highly underreported crime. But it’s unclear if the jump in harassment and retaliation complaints reflect a similar confidence or simply represent a growing problem.

Travis Air Force officials say they are encouraging victims to continue to come forward and hope the Sommer case does not deter them from seeking help.

“We know this is an on-going issue worldwide, and not just in the Air Force,” Racasner said. “We just feel for us, it’s all about educating folks, and ensuring individuals are being effectively taken care of.”

Air Force officials said military investigators are working with the Fairfield police on the Sommer case.

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

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