ARAPAHOE COUNTY, Colo. — A U.S. Air Force Academy captain and instructor described explicit sexual conduct to a girl he thought was 14-years-old and asked her if she was "into older guys", an arrest affidavit from the Arapahoe County Sheriff's Office says.

Paul Sikkema, 29, turned himself into authorities Wednesday morning and is being held without bond, a spokeswoman for the sheriff's office said. He faces a charge of internet luring of a child, which is a class 4 felony.

An investigator with the Arapahoe County Sheriff's Office posed as a 14-year-old girl named Jenny and began chatting with Sikkema online in January, the arrest affidavit says. After starting online, the conversation moved to text messages, according to the document.

Sikkema described "explicit sexual conduct to the 14-year-old girl" and also "made statements persuading her to meet for any purpose", the affidavit says.

According to the affidavit, Sikkema asked the investigator who he thought was teen, "are you a virgin?" He also stated, "I can get into a lot of trouble by talking to you" and at one point asked the teen for her address, the document states.

Investigators with the Arapahoe County Sheriff's Office contacted Sikkema by phone on April 23 and coordinated with his attorney to turn himself in the next morning, the affidavit says

As of Wednesday morning, Sikkema was still employed by the U.S. Air Force Academy.

"We are aware of the arrest and can confirm Captain Sikkema is a professor here at the Academy, a statement from the school says. "We are tracking his civilian court case as it goes through the legal process and will cooperate fully as needed with the Arapahoe Sheriff's Department. "

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