A U.S. Marine who allegedly arranged a sexual encounter with a man and his 12-year-old son and 11-year-old daughter promised that he “would bring Marine Corps shirts as gifts for the children” when they met to have sex, according to federal agents.

Stephen Lewis, a private first class stationed at Camp Pendleton in southern California, was arrested two weeks ago after driving 400 miles to rendezvous with a man he had met on Family4Love.com, a web site promoting incest and other illicit behavior.

The man who claimed to be the father of two underage children was, in fact, an undercover Department of Homeland Security agent. In a series of conversations with the investigator, Lewis--who is assigned to Combat Logistics Regiment 5--made his intentions clear, according to a federal court filing.

Lewis is pictured at right in a photo from his Tumblr page.

After being told by the undercover that he and his family believed in “love and sex regardless of age or society’s views,” Lewis replied, “That’s what I want to. I’ll come visit this weekend if you let me.”

“Who would I have sex with?” Lewis asked the undercover, who answered, “either son or dau.” The Marine later texted, “I’d make love to all 3 of you.”

During a text message exchange the following day, the undercover asked about “any fantasies that u want fulfilled with my dau.” Lewis replied, “Havering kids with her and fucking them, ducking your ass, her using a strapon on me, 3 way.” He then sent a clarifying note: “Sorry phone is auto correcting. Fucking her ass.”

Lewis also reported that he would go to Walmart and buy “masks to be worn while recording sex acts between himself and the children.” Lewis added that he would also purchase sex toys and bring Marine Corps shirts for the minors.

When Lewis was arrested en route to a September 14 meeting with the undercover at a Starbucks, he reportedly admitted traveling to have sexual contact with minors. He also copped to having images of child pornography on his phone and on his computer in his Camp Pendleton barracks. Agents recovered masks and a sex toy from Lewis’s truck.

U.S. District Court records indicate that Lewis is being investigated for enticement of children and possession of child pornography, both felonies.