LOS ANGELES » Dwayne Angebrandt wasn’t all that surprised when his bosses at the U.S. Department of Homeland Security asked their expert on sex trafficking to put together a public presentation on how to spot its signs.

What really took him aback was the audience he was asked to deliver it to: a group of strip-club operators.

For years, law enforcement had suspected such a group would likely be made up of some of the very people who are quietly selling women into prostitution. Or at the least, acting as middle men for people who do.

“I wondered where was the intersection with what our message is and what their message is,” he said of entrepreneurs whose business model is hiring women to dance naked in front of men and then paying them with only the tips the men offer.

But as the special agent in charge of the Southern California office investigating human trafficking quickly learned, many of the club operators and their dancers he met were surprisingly clueless when it came to spotting the problem.

Three years after his first presentation an unlikely alliance has formed between his agency and a group called Club Organizers Against Sex Trafficking. It’s one that seeks to train managers and dancers how to spot pimps and other traffickers who shadow their clubs and to report them to authorities.

Since the presentations have begun officials with COAST and Homeland Security Immigration and Customs Enforcement say several suspected pimps have been reported to authorities and a handful have been arrested.

“There was stuff they were telling us to watch for like if a girl comes in to audition and she has someone with her to speak for her, that’s a red flag. If she doesn’t have access to her own I.D., that’s a red flag,” said a 24-year-old dancer who attended a recent session in Denver.

“It’s stuff that sounds kind of fishy but I probably wouldn’t have put two and two together if I hadn’t had a class like that,” added the woman who dances under the name Tandy, and who like other dancers insisted she be identified only by her stage name out of concern for her safety.

“But, now, definitely, I would report it,” she added.

Michael Ocello, who operates 17 clubs and who founded COAST after one of them in Maine was raided as a result of a tip that turned out to be unfounded, said one of the first legitimate busts resulting from the training occurred at another of his clubs, in Denver.

An attractive young woman came to apply for a job accompanied by an authoritative woman who held the applicant’s I.D. and did all the talking while the prospective dancer sat nervously.

The nervousness wasn’t surprising, Ocello said, noting a career change to nude dancing isn’t something anyone takes lightly. But the training session had made his manager suspicious, and he asked to call the woman aside for a private audition. Instead, he asked why she wanted the job.

“The answers are simple. I lost my job, I’ve got to make tuition, I’ve got to make rent, I’ve got a kid, my husband lost his job, there’s a gazillion reasons, but they’re all going to focus on that financial aspect,” Ocello said. “But this woman said, ‘Well, this is where my friend said I got to work.’”

ICE was contacted and the woman arrested. Ocello didn’t know the case’s outcome, but he added he hoped his club manager saved someone’s life.

In Beaverton, Ore., a club’s call to police to report that it had discovered it was employing a 15-year-old runaway “with a very good fake I.D.,” led to the girl’s pimp being sentenced to life in prison.

In that 2014 case, said police Detective Chad Opitz, the club had been busted before for hiring an underage girl and was being careful not to let it happen again.

Opitz, who has attended a COAST training session himself, isn’t sure how much of an impact the efforts really have in influencing an industry he sometimes finds reluctant to cooperate with authorities. But he adds, “I think it can’t hurt. Awareness within the club is always very important.”

That’s what Angebrandt was counting on when he spoke to more than 100 club operators, and a handful of dancers, at a training seminar in the Los Angeles suburb of Burbank earlier this month. So far about 10,000 people have attended such gatherings nationwide, Ocello said, including recent ones in Houston, Louisville and Indianapolis.

Angebrandt told the Burbank group of a case involving a trafficker posing as a video producer who persuaded a woman to dance in a club in Atlanta. Soon he was pimping her for sex with club patrons. When she tried to return home he threatened her family.

“Was your industry a part of that?” he asked. “No, but it was your industry that was promoting it.”

Afterward, Chris Hassey, who operates a club in Sacramento, said the advice was “very informative, eye-opening.”

“I’m going to have a long talk with a couple of my girls when I get back,” he said, adding he was particularly concerned by the warning to watch for women leaving a club each night with a “boyfriend” they don’t seem to like.