The Army is investigating its top sex-crimes prosecutor on allegations that he groped a female lawyer at a sexual-assault conference in 2011, Army officials disclosed Thursday.

Lt. Col. Joseph Morse, who supervises 23 other special-victims prosecutors for the Army, was recently placed under criminal investigation after the female lawyer reported the alleged 2011 incident, officials said. News of the case was first reported Thursday by Stars and Stripes, a newspaper that covers military affairs.

Morse has not been charged in the case, but the revelation is the latest blow to the Pentagon as it struggles to cope with what some leaders have acknowledged is a epidemic of sexual assaults in the ranks.

News of the investigation surfaced just hours before the Senate was scheduled to vote on bills that would impose major changes in military law to strengthen the investigation and prosecution of sex crimes.

One of the bills would strip authority from commanders to oversee the prosecution of sexual assault and instead give that power to full-time military prosecutors.

Proponents have argued that military prosecutors are better trained to decide which cases should go forward and would be more likely to pursue complaints. The Pentagon has strongly resisted the bill, saying that commanders need to retain their legal authorities to ensure good order and discipline in the ranks.

The investigation of Morse could give ammunition to both sides. Victim advocacy groups and some lawmakers have said that the armed forces are too lax on sex crimes and that major legal reforms are necessary. But other lawmakers, and many commanders, say that giving more power to prosecutors won’t fix the problem.

The Army declined to comment publicly on the Stars and Stripes report. But two Army officials, speaking on condition of anonymity, confirmed that Morse was under investigation after a female lawyer who once worked for him reported that he groped her in a hotel room during a sexual-assault conference in Alexandria, Va.

Morse is chief of the Army’s trial counsel assistant program, which is based at Fort Belvoir, Va., and trains prosecutors throughout the Army. He also oversees nearly two-dozen special-victim prosecutors who focus on sex crimes, domestic violence and crimes against children.

Morse did not immediately return a phone call to his Fort Belvoir office seeking comment.

Last year, the chief of the Air Force’s sexual-assault prevention program was charged with assaulting a woman outside a bar in Crystal City, Va., and grabbing her buttocks. That case also ignited an outcry in Congress and among victims advocacy groups, but the officer, Lt. Col. Jeffrey Krusinski, was acquitted by a jury in November.

Also Thursday, a lawmaker grilled Army Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, over the military’s handling of an embarrassing episode involving raunchy and sexist e-mails written by an Army commander.

The commander, Brig. Gen. Martin Schweitzer, sent e-mails to two other Army officers in 2011 in which he called Rep. Renee L. Ellmers (R-N.C.) “smoking hot” and joked how he had masturbated “3 times over the past 2 hours” after meeting with the congresswoman. Schweitzer was later rebuked by the Army and his selection to be promoted to the rank of major general was placed on hold. The existence of the e-mails was first reported by The Washington Post in January.

On Thursday, during a hearing of the House Armed Services Committee, Rep. Jackie Speier (D-Calif.) asked Dempsey why the Army had not taken tougher action against Schweitzer. He is currently assigned to the Joint Staff and serves under Dempsey.

“I question what the punishment is when this general is now working for you, General Dempsey,” Speier said.

Dempsey replied that he couldn’t talk about the case because it “is part of an ongoing investigation.”