This latest arrest is part of what police say is a growing trend among teenagers and sexual predators. It's known as sexting. As our Neil St. Clair explains, it can lead down a dangerous path.

BINGHAMTON, N.Y. -- Gerald Koch, 49, a former soccer coach from Pennsylvania, is accused of sexual misconduct with a teenage girl with Binghamton ties. Koch, of Brackney, Pennsylvania in Susquehanna County, was arrested earlier this week after the girl's father became suspicious. A four-page indictment lists several counts stemming from a sexual relationship with the 16-year-old. Much of that relationship was captured via cell phone.

"It's nationwide. You can go online and look and there's cases that happen on a weekly basis," said Det. Sgt. Jason Ellis, a member of the Broome County Sheriff's Department.

This new form of predation is called sexting. Koch may have used it and so have others charged with sexually explicit relationships with teens. This includes former girls field hockey coach Todd Broxmeyer and Newark Valley teacher and former basketball coach John Puglisi.

Detective Ellis worked the Broxmeyer case.

"Anyone that's a predator, like Broxmeyer was, can be in the home and be violating those children without the parents knowing because they're not present," added Ellis.

Cells are usually meant for emergencies and while some come with parental controls, others, at a click of a button, can send out just about anything.

"It's going to get worse before it gets better. It's kind of this vague entity and I don't think we have our arms around it and I don't know if we ever will," said Raini Baudendistel, executive director of the Crime Victim's Assistance Center.

And the problem, police say, is that sex messaging or sexting isn't just confined to adult-minor relationships. Kids now are doing it between themselves.

"It certainly is a growing trend and not only like the most recent situation with an adult dealing with a female, but also with kids sexting and sending nude photos of themselves," said Capt. Alex Minor, a detective with the Binghamton Police Department.

A recent survey by the National Campaign to Prevent Teen and Unplanned Pregnancy shows around 20 percent of teenagers admit to sexting. This can sometimes result in child pornography charges. Police say the best thing parents can do is stay vigilant and communicate.

Several school officials we spoke say they just ask students to use common sense. Some also admitted sexting was a growing problem.