A U.S. senator questioned Wednesday whether the military erred when it dropped rape charges and discharged a soldier who later shot and killed two police detectives in California.

During the first Senate hearing on sexual assaults in the military in nearly a decade, Sen. Barbara Boxer, a California Democrat, cited gunman Jeremy Goulet as an example of what can go wrong when military cases are dropped.

"What is it going to take to convince the military that sexual assault is a violent and vicious crime and that those who perpetuate it, they're capable of other violent crimes, including murder," Boxer said at the hearing in Washington, D.C.

Goulet, who died in a shootout with police on Feb. 26 in Santa Cruz, Calif., was a helicopter pilot in Hawaii in 2006 when the Army court-martialed him on charges of raping two women. The charges were later dropped in exchange for an "other than honorable" discharge in 2007, officials said.

It's not clear why that was done, and the military records are not public. But under military law, a commander has the sole discretion in court-martials to reduce or set aside guilty verdicts and sentences or to reverse a jury verdict.

Rep. Jackie Speier, D-San Mateo, said the commander who decided not to prosecute Goulet needs to be held accountable. She intends to seek an investigation followed by a forum or hearing.

"This unit commander has such enormous power," she said. "This is a person who is not trained in law, and yet has the role of being a judge, making the decision if a case will move forward, who is going to serve time or walk away."

Meanwhile, former Defense Secretary Leon Panetta said the military should release records from the rape case involving Goulet and explain why the charges were dropped, the Santa Cruz Sentinel reported Wednesday.

Defense Department officials did not respond to repeated requests for comment.

Santa Cruz detectives Sgt. Loran Baker and Officer Elizabeth Butler went to Goulet's house last month to question him about allegations that he had been sexually inappropriate with a former co-worker.

While the detectives shouted through his front door, Goulet sneaked out the back and ambushed them.

After his death, investigators found the 35-year-old had ducked a string of sexual assault charges, both in and out of the military.

During a memorial for the detectives last week, Panetta surprised the thousands of people in attendance, saying the military needs to be more accountable.

"We do know that he had a history of sexual violence both in and out of the military, and for whatever reason, people somehow always look the other way," Panetta said. "At some point, somebody pays a price."