HAMMOND | A teen mother is preparing to reveal in Hammond federal court that the father of her 3-year-old baby is one of the men nabbed in a 2006 federal sting, court records state.

But the defense attorney for accused predator Mark Ciesiolka, 33, one of about two dozen men charged with trolling the Internet for underage sex partners during an August 2006 undercover sting by region federal agents, is trying to prevent jurors from hearing that revelation, arguing that having sex with a minor is not related to using the Internet to engage in illegal chats with minors.

Jury selection in Ciesiolka's case is expected to get underway today, and his trial in U.S. District Court in Hammond is scheduled to begin Tuesday.

The Ohio man was charged in the much-publicized sting operation in 2006 in which undercover officers posed as 13-year-old girls on Internet chatrooms and then waited for adult men to flock to them for sexual conversations and/or encounters.

Records filed by federal prosecutor Philip Benson in the Ciesiolka case state that the mother set to testify in the case came forward after reading of Ciesiolka's arrest in a media account of the sting. The mother was 15 when she gave birth but initially kept the identity of her "rapist" secret, Benson's filings state.

Benson states in the filings that DNA evidence proves Ciesiolka fathered the child. The victim alleges that the molestation began when she was 13.

"Beginning in approximately the summer of 2001, (Ciesiolka) engaged in the repeated rape and systematic victimization of a minor female who at the time was 13 years old," Benson wrote.

Defense attorney Kerry Connor disputes that in her court filings, arguing Ciesiolka "believes that there is only one instance of sex, if any at all," and that she intends to litigate the paternity claim.

"The alleged sex with Jane Doe, however, in not relevant ... because the factual context ... is entirely different than the context of the crime charged in this case," Connor wrote. "Mr.Ciesiolka did not use the Internet to persuade Jane Doe to have sexual relations with him."