Doctor John Mark Felton sentenced to 21 years in prison for plan to rape boy

A man described as a world-renowned doctor was sentenced to 21 years in prison for traveling to Alaska in a sting operation to have sex with a 5-year-old boy.

Dr. John Mark Felton of Boston was in a child-sex chat room in 2008 when he engaged in a conversation with a man he believed was offering his grandson for sex. The man was actually an undercover agent, The Associated Press reported.

When the 48-year-old Felton arrived in Alaska in 2009, he had a child's Spiderman costume in his luggage and condoms, according to court documents cited by the AP.

Felton, a British native, pleaded guilty last year to traveling to Alaska to engage in illicit sexual conduct, U.S. Immigrations and Customs Enforcement officials said in a statement.

He tried to argue that his chats weren't real, but prosecutors said Felton's sadistic sexual interest in children dated back to the 1990s, the AP reported.

When arrested, Felton had comprised a child pornography collection of at least 1,276 images of children being abused and 71 videos. He admitted making a video of himself having sex with a 15-year-old boy, according to the AP.

"Felton is a person with a long-standing sexual interest in children that he has satisfied, and attempted to satisfy, both through hands-on abuse and through accumulation of a treasure trove of child sexual abuse images and videos," prosecutors said in a court document referring to a psychological evaluation done as part of a plea agreement.

Felton was at one time vice president of clinical operations at a vaccine development company in nearby Cambridge, Mass., and developed vaccines to fight disease in third-world countries, according to the AP.