DALLAS (AP) - The girl curled herself into a ball as she rocked on a chair in the interrogation room wearing a halter top, short shorts and heavy makeup. Officers had spotted her walking a street on a weekday morning and suspected she was working as a prostitute.

Detective Michael McMurray walked in and handed her a T-shirt, crackers and a bottle of red soda.

"Why are you still doing this?" McMurray asked as he sat across from the 17-year-old girl.

Speaking with a soft drawl, she said the man she was living with "doesn't want me doing that."

McMurray didn't believe her. The girl had been picked up several times by officers in the last several years or sent to counseling to help her leave prostitution. This time, however, she was old enough to be considered an adult and was arrested for prostitution after further questioning.

This is exactly the kind of situation Dallas police are spending extra manpower to avoid.

In a city known as a national hotbed for prostitution, a special Dallas police unit is trying new approaches to identify and save underage girls being lured into the street life. Officers have adopted what they call a "victim-centered approach," making a list of every known juvenile prostitute and probing their pasts and ways to keep them out of trouble. And they're making a new push to use the Web - where for years traffickers have had almost free rein - to find girls and help them before it's too late.

"We can make survivors out of victims," said Lt. Fred Diorio, the head of the department's Crimes Against Children unit. "That's what we're trying to do. That's the goal."

It's a difficult one to achieve. While Dallas' effort has won acclaim for devoting extra resources to combat juvenile prostitution, officials and experts say web trafficking makes it harder to identify the girls and weed out the pimps. The girls are also sometimes reluctant to help prosecute their pimps and get them behind bars.

But experts say the strategies used in Dallas could be a model for other law enforcement faced with a problem that plagues most of America's big cities. They credit Dallas police for seeing juvenile prostitutes as victims and for working on the Web, something that confounds many big-city and small-town police departments with limited resources or knowledge about technology.

"You've got local police who are overwhelmingly undertrained in these issues trying to piece together how best to respond to a crime that increasingly has a technological element to it," said Jennifer Musto, a researcher on anti-trafficking methods at Rice University.

The Dallas Police Department's High Risk Victims unit consists of three detectives and a supervisor, part of a 35-detective Crimes Against Children division - a significant allotment devoted to an issue most departments lack resources to adequately address.

Part of the police unit's strategy has been identifying about 350 high-risk victims each year - children and teenagers who are repeat runaways, prostitutes or sexual assault victims. As many as half are believed to be prostitutes or involved in trafficking.

A small group of officers in the unit is responsible for interviewing the girls when they're found. They ask about their home lives and probe for information that could be used in a future trafficking prosecution.

The stakes are high. Police see their best chance to save girls when they're younger since many of them are nearly impossible to reform when they reach adulthood.

In June, the police staged a sting they called "Operation Brick and Mortar" - a reference to how the physical building where prostitutes and pimps once congregated had largely migrated to an online setting. For four days, officers answered online sex ads on Backpage and other sites, posted their own ads to deter johns and made arrests. A later sting netted more than 40 arrests.

But the challenges of finding juveniles were obvious.

Catherine De La Paz, a veteran detective, was in charge of picking out ads she thought might offer juvenile prostitutes. Police dialed numbers and contacted each of the 99 ads she picked. Most of the numbers came up busy, but they eventually made contact with 22 ads and detained 23 people for prostitution. Just two were under 18 years old.

De La Paz demonstrated why it was so difficult. On a recent weekday, she scrolled through an online classified site with sex ads. The ads pop up four at a time - dozens of women, some of them posing naked, with a phone number and a price listed. Deciding which girls were underage proved a guessing game.

But technology could eventually simplify the process of tracking prostitution online. Researchers and programmers are working to develop facial recognition software or programs to filter keywords that commonly pop up among juveniles. It's likely years away from widespread use.

"We're automating that process for them," said Mark Latonero, a University of Southern California researcher who authored a report published last year on online human trafficking. "It automates a laborious process which is already being done right now in a very slow way."

Meanwhile, police acknowledge they're playing catch-up to web traffickers. When one juvenile is found, many pimps move to another source of prostitution. And those who are caught are sometimes difficult to prosecute because victims can make difficult witnesses at trial.

"You've got sometimes very damaged individuals who are involved, and you can't just start asking them 100 questions to start your prosecution," said U.S. Attorney Sarah Saldana, the top federal prosecutor in Dallas.

Nationally, the number of federal human trafficking prosecutions hit an all-time high in 2010, though numbers differ on how many girls are involved in juvenile prostitution.

Police in Dallas say many of the girls they have documented come in from other cities. They often refer girls to a local shelter for counseling and treatment. A long-term shelter for juveniles under construction in Dallas County will soon provide another option for rehabilitation.

Officers say their effort is still too new to gauge how successful it has been. In the meantime, they are learning more about the Web, expanding their work with girls and hope to run more stings in the coming months.

Paige Flink, director of The Family Place shelter, which deals with battered women and victims of abuse, credited police for their tactics.

"I think that we have a more sensitive police force," Flink said. "Rather than criminalizing this girl who's basically been kidnapped in some cases, they're realizing that it's the environment, what was done to her, not what she did."

(Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)

9/8/2012 12:22:24 PM (GMT -5:00)