Authorities have arrested and charged a Duke University official who they say offered his adopted 5-year-old son for sex.

The FBI's Washington field office said the school's associate director of the Center for Health Policy, Frank Lombard, was caught in an Internet sting.

Authorities said that Lombard tried to persuade a person — whom he did not know was a police officer — to travel to North Carolina to have sex with Lombard's child.

Court documents charge that Lombard identified himself online as "perv dad for fun."

The papers also say an unnamed informant, facing charges in his own child sex case, tipped off authorities to Lombard's activities.