VASSALBORO, Maine — Late last fall, an out-of-state man on a private crusade against online child erotica found a website that purports to sell vintage-style underwear to boys, teens and men.

But what it actually sells, he believes, is access to photos of youths who are primarily cavorting in underwear. The man was able to identify and track down one of the boys because in one photo the child was dressed in his school baseball uniform from a central Maine elementary school. When the Internet whistleblower contacted local police officials, they were appalled.

There is “enough information that people know exactly who these kids are,” said Lt. Glenn Lang of the Maine State Police’s Computer Crimes division. “I think parents need to be deeply concerned about it. If someone can identify who your child is, or where your child is, on a website, where a guy from God knows where can say, ‘I know exactly what school your child goes to,’ that’s a recipe for disaster.”

The boy is one of several central Maine youths who were paid to model for the website, which neither Lang or the Bangor Daily News is naming because it has not been charged with a crime. After investigating the underwear company, police could not bring charges against it, he said — because the photos did not contain a “lewd display” of genitals, or show a sex act, they did not cross the line into child pornography.

But Lang was clear in defining the website, and others that are similar that easily number in the hundreds, as child erotica.

“You’ve got to ask yourself: Are they marketing the children or the product?” he asked. “A lot of them operate right on the raggedy edge of the law.”

Federal law defines child pornography as any visual depiction of sexually explicit conduct involving minors under the age of 18. The law prohibits possessing, manufacturing, distributing or accessing with the intent to view child pornography. All 50 states and the District of Columbia also have laws which make the possession, manufacturing and distribution of child pornography illegal, according to the website for the National Center for Missing and Exploited Children.

In other states, including Washington and Connecticut, law enforcement agents also pursued an investigation but ran into the same problems that Maine police did, Lang said.

“It doesn’t appear that there’s anything we can do about this particular thing,” he said. “But when you start having local victims … and when you take a low-angle picture of two boys wrestling with a hose spraying them and you can barely see the product they’re selling, come on.”

Maine law enforcement officials approached the boys’ parents, to alert them of their concerns, but the reaction they received was lukewarm at best. The boys had been paid “in the hundreds of dollars” for the photo shoots, and the parents did not believe that there was any wrongdoing by the underwear company, Lang said.

“Parents are often very proud of their children. They think their children are beautiful, and that’s a great thing, but they have to realize, some people look at children in a whole different light,” Lang said. “There’s going to be a defensive mechanism there, where they’re trying to rationalize it. But even if they’re doing nothing more than it appears they’re doing, these children are getting exploited.”

An official at the Washinton-based firm who answered the phone last week said that it is a “decent” company, which finds its models through a talent agency and then hires photographers to shoot the pictures. Its products appear to only be sold online, although Lang suggested that the company likely sells more photo catalogues than underwear to its clientele.

Maine police believe that the modeling agency that contributes photographs is located in Connecticut, but the company official would not identify that agency or other talent agencies in Maine that it uses.

The man grew indignant when told of the police investigation and he terminated the conversation.

According to Lang, mainstream clothing companies, including J.C. Penney and Sears, no longer show children wearing underwear and bathing suits in their catalogues.

Caron Bryan, owner of Port City Models & Talent Inc., in Portland, said she has been in the business a long time and knows that there are many predatory outfits that want to take advantage of people with modeling stars in their eyes.

“I’m extremely careful,” she said, adding that she does not have her models do anything that might be considered to be exploitative of children.

The industry is largely unregulated, she said, and often preys on naïve parents or children.

“There are so many people who aren’t realistic,” she said.

Bryan said that one way that type of company can profit from young people who flock to model searches is to charge them a lot of money for a portfolio of photographs. But she also said that parents should be careful to research modeling agencies, clients and photographers who have indicated an interest in their children.

“Parents have to be so, so careful,” she said. “There’s so many parents who want their children to get in this business. But oh, my God, you have to be so extremely careful.”

Lang said that parents with questions about possible modeling opportunities for their children should be fine if they use some common sense. They should never leave their kids unattended during a modeling shoot, he said, and also should see all the photographs.

“They should be skeptical at all times of how the photos are being taken,” he said.

If parents have questions about a particular company or modeling shoot, they are encouraged to call local law enforcement agencies.

And they should simply be aware that “modeling underwear” is a red flag when it comes to child exploitation, he said.

“A parent should immediately say, ‘Are you kidding me?’ Reputable companies just aren’t doing that anymore,” Lang said.