If you need more evidence that much of the U.S. military treats sexual assault like one big frat-house joke, look no further than what allegedly happened outside a Crystal City bar in the early morning hours of Cinco de Mayo.

That’s where the 41-year-old lieutenant colonel in charge of the Air Force’s program to prevent sexual assaults allegedly groped a woman’s breasts and buttocks in a parking lot.

The Arlington County police report said he was drunk. And if you’ve been wondering why he had cuts on his face in the police mug shot, a witness told me that the woman pulled out a cellphone and started hitting him with it.

Lt. Col. Jeffrey Krusinski was “removed from his position immediately” when the Air Force learned of his arrest, an Air Force spokeswoman said. But then something revealing happened: The military tried to take the case away from Arlington authorities.

Defense Department officials asked the Arlington commonwealth’s attorney, Theo Stamos, to just turn it over to them. Don’t bother with your little county court stuff. Why don’t you just let us handle our boy over here at the Pentagon?

This image released by the Arlington (Va.) County Police Department shows Lt. Col. Jeffrey Krusinski. (Associated Press)

But Stamos, to her credit, refused.

“They did ask that we relinquish prosecution, and we didn’t,” said Stamos, who has spent a career working just beyond the Pentagon’s doorstep.

“Obviously, being where we are in Arlington, we have to prosecute members of the military routinely,” Stamos said. But this was the first time in her two decades as a prosecutor that the military asked for a case, and she was surprised by the request.

The case was on her turf.

It had been a slow night in Arlington: a stolen Buick LaSabre and a burglary in which a Dell laptop, a gold ring and $60 were taken. So cops responded quickly when the woman called for help about 12:30 a.m. Sunday.

Cpl. Geoffrey Gammell of the Arlington police arrived, a man as beefy and close-cropped as Krusinski, and treated the incident with the seriousness it deserved. He booked Krusinski on a misdemeanor charge of sexual battery. If convicted, Krusinski faces up to a year in prison.

Krusinski declined to comment on the case when approached after his arraignment Thursday in Arlington County General District Court.

Some people say Krusinski is a familiar figure along a faded strip of restaurants and pubs in Arlington. It’s walking distance from the Pentagon and his apartment. One waitress I interviewed recognized his booking mug right away: “Oh, he’s the one who orders just sausages” when he’s been drinking.

“He’s nice!” she said. “I feel bad for him.”

Krusinski, an Air Force Academy graduate with lots of military medals, a $132,000-a-year salary and no public record of lawbreaking, is a guy who uses a picture of a football field as his Facebook profile photo, stays in touch with his high school wrestling buddies from Ohio, and lists sports pubs and Malcolm Gladwell books as Facebook “likes.”

At one of his “liked” bars in Arlington, the folks said he’s a regular. He’s known as a nice guy, no problems. At another, the bartender told me I had to talk to the owner when I asked her if she knows Krusinski.

One of her customers — a guy with his federal identification badge hanging from his neck, a pint in front of him and an unlit cig dangling from his lips — threw his head back and laughed. “As your personal, public affairs specialist, I say: Well played,” he told the bartender.

The owner, who offered a friendly handshake and a bright smile, said he’d never seen Krusinski there.

The person I really want to talk to is the woman who smacked him with her cellphone. (The witness to the incident asked not to be identified.) She’s my new hero. His rank didn’t matter one bit to her, if she was even aware of it.

But that kind of assertiveness hasn’t been celebrated in the armed services. Military women brave enough to denounce their attackers have often been ignored or even punished. And the lax attitude toward sex offenses may not be limited to men, either.

The day after Krusinski’s arrest, we learned that Air Force Lt. Gen Susan J. Helms, who is also an astronaut, had granted clemency this year to a captain convicted of sexual assault. She explained in an internal memo that she found the captain’s testimony more credible than his accuser’s, The Washington Post’s Craig Whitlock reported. Her decision may cost her a promotion.

A similar thing happened in February. Air Force Lt. Gen. Craig A. Franklin tossed out a star fighter pilot’s sexual-assault conviction and ordered his release from prison. An Air Force spokesman said Franklin tossed out the jury verdict after reviewing the entire trial record and finding that the evidence did not prove guilt beyond a reasonable doubt.

As the Cinco de Mayo haze cleared on Siete de Mayo, the Pentagon released a report showing a 35 percent increase in the estimated number of military personnel victimized by sexual assault and related crimes over two years. An anonymous survey had found that 26,000 people — men and women — experienced “unwanted sexual contact” last year, up from about 19,300 in 2010.

The Defense Department also recorded 3,374 reports of sexual assault in 2012, compared with 3,192 the previous year.

Some studies estimate that only about 17 percent of military victims of sex offenses report the attacks, making it difficult to know the extent of the problem.

The military needs to start taking this problem seriously, because it seems to keep getting worse.

Gammell was right to arrest Krusinski that night. And Stamos deserves kudos for refusing to turn the case over to military investigators.

Hey, Pentagon commanders: Look beyond that 395 freeway on-ramp, just past the McDonald’s and Macy’s, and see how allegations of sexual assault ought to be dealt with. Like a potential crime.

To read previous columns, go to washingtonpost.com/dvorak.