Bill Roche was so close to his dream job. An overachieving police officer in a Bay Area suburb, Roche had made detective while still in his 20s. Confident that his law-enforcement resume was sufficiently impressive after seven years on the force, he applied to become a U.S. Secret Service agent in 1997. Throughout the yearlong selection process, his interviewers lauded him as an excellent candidate. But before he could earn his earpiece and Ray-Bans, there was one last detail to take care of: Roche had to submit to a lie detector test.

No problem, he shrugged. After all, Roche had already passed three polygraphs over his police career. But not long after he arrived at the Secret Service's field office in San Francisco, things started to go awry. Roche was hooked up to a computer set to monitor his breathing and perspiration, and says he answered each question as truthfully as possible. But as the seven-hour session wore on, the polygrapher grew increasingly angry with Roche's responses, insisting that his physiological reactions "were not in the acceptable range." He accused the veteran cop of withholding information about his drug use, his criminal history, and his honesty on the job. The more strenuously Roche protested his innocence, the more confrontational the examiner became. "At one point, he's sticking his finger right in my face," recalls Roche, "and he's yelling stuff like