For more than a year, John Mark Felton chatted online with an Anchorage father of two, planning a visit to meet the family so he could molest a 6-year-old boy, according to documents filed in federal court.

He talked about a scene in which the father would molest his 7-year-old girl and Felton, a Briton living in Boston, would molest the 6-year-old.

"I'll come there if you're offering to let me play nicely with your son," Felton wrote during the conversation, according to documents charging him with traveling across state lines with intent to engage in sex with a child. "really wanna find a very discreet dad for some fun like this."

Felton, 45, was arrested Monday night after getting off an airplane at Ted Stevens Anchorage International Airport, when he learned the father he had been talking to was in fact Special Agent Kevin Laws with Immigration and Customs Enforcement, and that the family Laws portrayed was a ruse.

According to a resume that investigators turned up online and that includes Felton's picture, he is a research physician currently working as vice president of clinical operations at Acambis, a vaccine development company. He previously worked as senior medical director at GlaxoSmithKline, his resume says.

He was working in the United States on a valid visa, according to an affidavit.

On Feb. 28, 2008, Laws was undercover in a chat room called "#Litlleboysexchanel" when Felton approached him and eventually proposed he come to Anchorage.

"you into anything the kids or I should be worried about," Laws wrote.

"nope, very clean, healthy and discreet. not into anything nasty. just really into kids," the user replied, according to Laws' affidavit.

Investigators later traced the user's IP address back to a property Felton owns in Boston, Laws wrote.

The men again conversed in online chats on April 17, 2008, when the same user "again graphically explained his desire" to molest the undercover's son, Laws wrote. The agent sent the user some pictures purporting to be of himself and the kids, who were clothed and with their faces blacked out.

Laws did not hear from the user again until Sept. 18 this year, when the man wrote him saying he missed the "chats about our shared interests," Laws wrote in the affidavit. The man then discusses steps they should take to avoid detection including that they shouldn't have each other's names, addresses or photos.

They exchanged e-mails over the following weeks planning the trip, Laws wrote.