A U.S. Air Force Academy captain who teaches ethics at the school in Colorado Springs has been arrested for suspicion of internet luring of a child, according to the Arapahoe County Sheriff’s Office.

Paul Sikkema, 29, is being held in the Arapahoe County Detention Center on a $7,500 bond on accusations that he traded sexually explicit messages with a sheriff’s deputy posing online as a 14-year-old girl, according to his arrest affidavit obtained by The Denver Post.

ACSO Internet Crimes Against Children investigators have arrested Paul Sikkema, a captain and instructor at the U.S. Air Force Academy on the charge of internet luring of a child, a class 4 felony. pic.twitter.com/qp0zengk1I — Arapahoe Sheriff (@ArapahoeSO) April 24, 2019

On Jan. 21, an Arapahoe County sheriff’s deputy, who was portraying a 14-year-old named Jenny, met Sikkema in an online chat room, the arrest affidavit said. The conversation moved to text messages and, over the course of a week, Sikkema allegedly sent graphic messages about sex and asked for an address he could visit.

On Tuesday, sheriff’s investigators contacted Sikkema over the phone, and he turned himself in on Wednesday after coordinating with an attorney, the affidavit said.

Sikkema, a 2012 graduate of the U.S. Air Force Academy, teaches ethics in the philosophy department. He majored in legal studies and philosophy while a cadet, according to his profile on the academy website.

After graduating from the academy, Sikkema earned a master’s degree in philosophy from Georgia State University where he wrote a thesis on the ethics of targeted killing, the academy’s website said.

After finishing his master’s degree, Sikkema attended undergraduate intelligence officer training and then was assigned to the 337th ACS at Tyndall Air Force Base in Florida where he served as an instructor for undergraduate air battle manager training.

Sikkema returned to Air Force Academy in 2017 to teach in the philosophy department.

This story is developing and will be updated as more information becomes available.