BOSTON -- Online predators are using their potential victims to stay one step ahead of the law, according to a Team 5 investigation.

NewsCenter 5's Janet Wu reported Tuesday that online predators are luring children and then using them to cover the criminal's tracks.

"When I was 15, I met a man on the Internet. His name was John," Katie Canton said.

It was before the term 'Internet sexual predator' was even invented. Canton's parents knew about him, but thought the relationship was harmless since John lived across the country.

"They didn't really want to interfere because they didn't want to break trust with me," Canton said.

But what she didn't tell them was that he was sending her gifts, pledging his love and offering marriage. It all ended when he bought a plane ticket to visit her. Her parents notified the police who gave them an Internet game called Missing. Players become detectives, tracking down pedophiles. Canton said that she resisted at first.

"Red flags were going up in my mind. The Internet predator in the game had a lot of similarities to John," she said.

John turned out to be a pedophile, who is now serving 20 years in federal prison for sexually assaulting another teenager, thanks to Katie's testimony and good police Internet forensics. But that was five years ago. Investigators said while predators still have the same motives, they are now far more devious.

"Predators have become much more sophisticated than probably 80 percent of the kids and 90 percent of the cops," Raynham Police Department Chief Lou Pacheco said.

"The predators know we're looking for them. They will talk to our kids, tell them to keep things off their history list, keep things off their cookies list, make sure those things are not there," Plymouth County District Attorney Timothy Cruz said.

Last summer, Cruz, with the help of federal and state agencies, set up a sting operation that arrested 13 men. But too often, he said, a missing child leads to a computer hard drive that's been wiped clean.

"There's all these third-party programs that the kids can load down that completely wipes their tracks out. The predators know these things and point the kids in that direction," Pacheco said.

Some predators also ask their victims to take their laptops to their first meeting so they can personally destroy the evidence. Yet sometimes police track down pedophiles with the slimmest of information.

Detective David Papargiris runs the Metropolitan Law Enforcement Council's computer lab. He described tracking down one pedophile who sexually assaulted a young girl, lured through the Internet by conducting forensics on his computers.

"I would say law enforcement is probably 60 percent more trained now that we were five years ago," he said.

"They act. We react. They act. We react," Pacheco said.

Pacheco said sting operations are too often compromised.

"They're very sophisticated at determining if they're being set up or if it's really a kid," Pacheco said.

Canton said that she knows she was lucky. She warned teenagers that today's predators are very different.

"They're good at it. They know every trick in the book," she said.