It was the third bust of a Central Florida sex-trafficking ring in as many days. Fed up, the leader of one law enforcement agency looked into television cameras and issued not a warning, but a promise.

"Backpage," Polk County Sheriff Grady Judd said, referring to the web-based classified ad service Backpage.com implicated in all three cases, "you're going to be criminally investigated and so are the people that are in charge of the organization.

"It's abundantly clear to us that they are facilitating organized prostitution. They are facilitating human trafficking," he said, adding, "We're not going to have that."

While Pinellas County Sheriff Bob Gualtieri and Clearwater police Chief Anthony Holloway agree with Judd that Backpage should be investigated, they say their priority is catching the pimps and helping the victims of human trafficking. Both agencies earlier this month announced busts of six people they say advertised on Backpage and forced local girls and teen runways into prostitution.

"The common denominator," Gualtieri said, "are the exploiters — those people who are recruiting the girls, helping them get customers, threatening them with violence if they don't comply and then reaping the financial benefits. I think that's where we need to focus. And really rescue these girls."

The scrutiny is nothing new for Backpage.

Users of the Dallas-based paid listings site can barter everything from furniture to roommates to local events. But it is best known for its adult-services section, where a May 2012 Arizona State University study estimated nearly 80 percent of ads were for prostitutes and that 10 percent of 900 such ads posted during eight days in metro Phoenix featured girls under age 18.

Authorities in the Central Florida cases say pimps and johns used the site to arrange dates with the prostitutes.

Judd said Backpage is complicit because it charges higher fees for adult ads than other types of listings. Authorities say users routinely violate the site's rules against code words by employing obvious euphemisms, such as "donation" or "roses," for cash exchanges.

However, Backpage attorney Liz McDougall said in an email that the company is concerned about human trafficking, too. She commended sheriffs Judd and Gualtieri for their dedication to combating "this scourge" and said the site would "welcome the opportunity" to work with them.

According to McDougall, Backpage's triple-tiered policing system includes an automated filter that screens for 36,000 terms. She said a round-the-clock team of some 80 staffers checks ads before and after publication.

The site, she said, also works with a national trafficking shelter, uses an expedited system to report about 25 potential trafficking victims per day to the National Center for Missing and Exploited Children, and helps police investigate traffickers by gathering additional evidence from other websites.

"Vilifying" Backpage, McDougall said, would only push the problem elsewhere, as evidenced by cases in Ireland and Finland.

"Unless the Internet is wholly shut down," she wrote, "the end result of this strategy will be that our children are advertised through offshore websites ... who are outside the jurisdiction of U.S. law enforcement so they can thumb their noses at U.S. law enforcement requests, even pleas, for evidence to find a child or stop a perpetrator."

Holloway and Gualtieri agreed, adding that some local hotel owners also help facilitate or turn a "blind eye" to obvious prostitution through practices like renting rooms by the hour.

"You need to clamp down on (the hotels) but all you're doing is squeezing the balloon. They're just going to go elsewhere," said Gualtieri, who has already budgeted funds for two more Crimes Against Children detectives.

Backpage, added Holloway, "needs to be shut down but it's a good investigative tool for us right now for trafficking. As soon as you shut down Backpage, I guarantee you, in the next three or four days, the problem will go" to a different site.

Judd declined to comment on his investigative strategy regarding Backpage.

Clay Calvert, director of the University of Florida's Marion B. Brechner First Amendment Project, noted that Backpage has successfully struck down attempts in Washington and Tennessee to force the site to verify users' ages.

While the U.S. Constitution doesn't protect commercial speech that hawks an unlawful good or service, he said, it's difficult to enact laws prohibiting sexy ads like those posted on Backpage because of the potential for inadvertently blocking legitimate posts.

Keyonna Summers can be reached at (727) 445-4153 or ksummers@tampabay.com.