Richard Kemper, a Hillsborough County middle school teacher was among 13 people who were arrested in an internet prostitution sting in Polk County.

The Polk County Sheriff's Office said the popular classified Web site Craigslist targeted men who used the site to look for sex. They were then lured to an undercover house in Winter Haven.

Kemper, 50, was arrested after he offered an undercover agent $ 150 for sex. A software developer, paint-store manager, citrus buyer and truck driver were others arrested.

 Polk County Sheriff Grady Judd said, "Our message is pretty straightforward, if you want to engage in prostitution, stay out of our community."

Hillsborough County schools spokesman Steve Hegarty said Kemper has been a teacher at Randall Middle School for about 3 1/2 years. He said only the school board can suspend a teacher without pay and in similar cases, teachers have been asked not to report to work and have been suspended with pay until the school board takes action.

Judd said the stings were meant to protect unsuspecting partners who might contract diseases such as HIV and hepatitis from spouses who have engaged in prostitution. "It's anything but a victimless crime," Judd said. "They go home to an unsuspecting wife." He added that his office would continue to be alert to sex crimes and plans to have detectives look into any criminal liability that Craigslist might have for running the advertisements. "I think Craigslist does a lot of good things, but they can't hide behind the First Amendment to enable criminal activity," he said.

The sting, which ran Thursday through Saturday, had 12 additional arrests, including: George L. Gressett, 74, of Poinciana; John Charles Renna, 44, of Lakeland; Mark Allyn Graffrath, 45, of Lakeland; Bradley Richard Lowe, 37, of Winter Haven; Thomas David Castle, 50, of Riverview; Anthony Avery Harvard, 52, of Winter Haven; Gregory Daniel Polk, 33, of Apopka; Kerry K. Saruwatari, 44, of Lakeland; Richard F. Kronz, 42, of Davenport; Terry Gene Lipply, 45, of Lakeland; Gerald S. Chrethien, 56, of Plant City; Randy Thomas Whitfield, 42, of Lakeland.