Brandon Thompson, 28, who is also known as 'Kadafi' and 30-year-old Megan Hayes are both charged with federal sex trafficking. According to court papers, the alleged crimes date back to April and involve at least three underage girls.  According to court papers, the young girls were being advertised on the Web site BackPage.com.

It's a lot like Craigslist. But if you recall, Craigslist began policing its web site earlier this year, cracking down on alleged prostitution offers.

BackPage's terms of use agreement also states that the Web site's administrators reserve the right to remove any ad for services which violate federal, state or local law. Ads can also be removed, it says, for posting obscene or lewd and lascivious graphics or photos.

The site allows users to narrow their viewing by state, and includes such categories as community and jobs. It's the adult section however, where we found the questionable material under the heading of escorts. That's the same category authorities say Thompson and Hayes were using to list young girls. It took us to a long list of postings from women with pictures and suggestive titles. Some listings also include prices

We contacted the BackPage Web site by email as to why such ads were being allowed on the site since they appeared to violate the terms of agreement. We have received no answer from the company.

Sioux Falls detectives tell us they monitor Web sites like BackPage, but they're hard to police because the suggestive postings are advertised as escort services and that's not illegal.