"We have to keep up on their code. We have to find out what are the popular bands, what movies are out there."

The Utah ICAC task force recruited a 15-year-old boy as a "consultant" to teach them about video games, pop culture and bands.

In another window, someone sent McQuiston a video clip of hard-core pornography.

"Sometimes you'll find some drunk horny guy that wants sex with a child now, and they're the ones that we worry the most about," he said. "Because if they don't end up finding us and wanting to have sex with us, they're going to find a kid somewhere and they're going to meet and bad things are going to happen."

Tough job

McQuiston has arrested more Internet predators than anyone else in the United States, the Utah Attorney General's Office says.

"He's extremely adept at adopting the persona of an underage teenager, whether it's a girl or a boy," Wallentine said. "He is 110 percent committed to the notion of protecting children."

McQuiston came to the ICAC task force from the Utah Department of Corrections, where he worked as an investigator.

"I was the youngest investigator at the time — 27 — and they figured I knew the most about computers," he said.

He joined the ICAC task force as a part-time member, working his way to be assistant section chief.

It's not easy to do this job. Agents are barraged with horrific images and videos of children being violated. They talk regularly with people trolling the Internet for kids. Some agents work part time, on loan from other law enforcement agencies.

To get on the ICAC task force, officers are screened rigorously.

"They understand what they get into," Ahearn said, adding that agents regularly undergo psychological evaluations.

"I don't think anyone will tell you this kind of work is particularly fun," Wallentine said. "I don't think I've ever worked with cops that have a greater team spirit. I don't think I've ever seen a unit that's cohesive, that clicks better. People can finish each other's sentences. It is a chief's dream."

Ahearn said the job demands physical and mental toughness. The arrests and interviews sometimes come on a second shift, long after the cyberchats are over and the sting is set up.

"It's hard to burn out when you know you're doing something so incredibly valuable to the community," Wallentine said.

Avoiding entrapment