AdvertisementFBI's Vicious Letter To King Holds Lessons On Surveillance, HindsightNovember 13, 2014Sam SandersfacebookEmailWilliam Sullivan, former assistant director of the FBI, chats with newsmen prior to his appearance, on CBS' "Face The Nation," in 1975. Sullivan is believed to have written an anonymous letter to Dr. Martin Luther King Jr. criticizing him for his personal life. (AP)