** FILE ** In this April 28, 2994 file photo, former CIA agent Aldrich Ames leaves federal court in Alexandria, Va. Ames beat the polygraph test twice and now the Defense Intelligence Agency is nearly tripling its arsenal of lie detectors in an attempt to polygraph every one of its 5,700 prospective and current employees every year. Polygraphy as a screening tool, however, is not fool proof. The test gives a high rate of false positives on innocent people, and guilty testers can be trained to beat the system. (AP Photo/Denis Paquin, File)