The arrest was a result a months-long probe, said the U.S. attorney for the Southern District of Indiana, Joseph Hogsett.

“The mission of our Project Safe Childhood initiative is to investigate and prosecute anyone found to (be) engaged in the sexual exploitation of children,” Hogsett said in a news release. “No matter who you are, you will be brought to justice if you are found guilty of such criminal behavior.”

Sachtleben is currently an Oklahoma State University visiting professor, according to his online resume. He is director of training at the school’s Center for Improvised Explosives, but all references to his work have now been removed from the university’s website. There was no indication from the school as to whether it had suspended him. Calls to the university and his Indianapolis attorneys were not immediately returned.

He had been an FBI special agent from 1983 to 2008, serving as a bomb technician. He worked on the Oklahoma City bombing and Unabomber investigations, according to his university biography.

A separate LinkedIn profile filled out by Sachtleben says he is an “accomplished investigator with more than 25 years of experience in FBI major case management, counter terrorism investigations, bombing prevention, post blast investigations and public speaking.”

According to the criminal complaint, a federal-state joint task force had been investigating an Illinois man allegedly trading child porn images as far back as September 2010. That suspect was arrested in January, and a search of his computer reportedly led to Sachtleben, who was using the e-mail name pedodave69. ( the user name looks like a set up)

According to the affidavit, an e-mail from that account was sent to the Illinois suspect last fall, along with nine images of child porn. “Saw your profile on (a file sharing network). Hope you like these and can send me some of ours (sic). I have even better ones if you like.” Prosecutors say Sachtleben sent that e-mail.

Sachtleben’s wife was interviewed by agents during the execution of the search warrant and denied any involvement with child porn. She was not taken into custody.

FBI officials in Washington had no comment on the arrest.

If convicted, Sachtleben would face up to 20 years in prison on the charge of distribution of child porn, and an additional 10 years for possession.

The Justice Department’s Project Safe Childhood initiative was launched in 2006, leading to what federal officials call a more than 40% increase in the number of cases investigated. The project’s website says 2,700 indictments were filed last year alone.

The case is U.S. v. Sachtleben (1:12-mj-316).