Reporter Jon Ronson tells the story of how, in the immediate wake of September 11, he became convinced that a man he'd done a story on was responsible for the Anthrax attacks in America. So he did something he'd never done before, he ratted out his source to the FBI. He then felt the guilt of accusing someone who turns out not to be guilty. Jon Ronson is the author of the book, Them: Adventures with Extremists. (18 minutes)