WATERLOO - As the top federal prosecutor for Northern Iowa, Matthew Dummermuth is in the business of putting sexual predators in prison.

On Friday, Dummermuth was in Waterloo to prevent children from becoming victims.

A gym full of local Catholic middle school students at Blessed Sacrament listened as the United States attorney talked about the dangers of meeting people in the Internet.

"The person you meet online might not have your best intentions in mind," said Dummermuth, whose presentation included a number of public service videos from www.netsmartz.org.

Nearly all of the hands went up when Dummermuth asked how many students use the Internet. Most hands stayed up when he asked how many use social networking Web sites or chat with friends on the computer.

The presentation showed how easy it is to track down information about a person using just their online screen name and innocent details in their profile.

Dummermuth said predators can do the same or slowly glean such details after striking up conversations with youths in chat rooms or though instant messages.

And the outcome can be serious, said Dummermuth, who recounted how an Iowa man coaxed a 14-year-old Pennsylvania girl to come to the Midwest after meeting her on the Internet.

In fact, the U.S. Attorney's Office for the District of Northern Iowa has gone from having one prosecutor for handling child exploitation cases 10 years ago to having four prosecutors covering the subject today.

"The most typical victim that we see is middle school kids," Dummermuth said.

Other topics covered in the presentation included cyber bullying.

The office did an Internet safety presentation in the spring and then picked up the pace when the school year started in September.

For more information about the presentation, contact the U.S. Attorney's Office at (319) 363-6333.

Contact Jeff Reinitz at (319) 291-1578 or jeff.reinitz@wcfcourier.com.