Donald Sachtleben was an FBI agent for 25 years, with a record that includes such high-profile investigations as the Oklahoma City bombing, United Flight 93 and the Unabomber.
Now his record includes child pornography charges.
Federal investigators in Indiana arrested 54-year-old Sachtleben this week after they allegedly found 30 images and video files of child pornography on his computer, along with evidence that he distributed the material, according to the Chicago Tribune.
Fox 59 reported that Sachtleben traded the explicit photos and videos using the e-mail address "firstname.lastname@example.org."
In one e-mail, Sachtleben allegedly sent someone nine photos containing the material and wrote, "I have even better ones if you'd like."
He faces 30 years in prison if convicted. His attorney, Kathleen Sweeney, told the Associated Press that he pleaded not guilty on Monday.
According to his LinkedIn profile, Sachtleben was an FBI explosives and counter-terrorism expert for 25 years, briefly taught at Oklahoma State University's Center for Health Sciences and examined "more than 150 improvised explosive devices" in the field and in labs. He retired from the FBI in 2008.
His next hearing is scheduled for Thursday.