National Geographic : 2003 Nov
BODY CHECKS Fingerprint identification has been used to solve crimes since the days of Sherlock Holmes, but the practice took a giant step forward in 1999 when the FBI began using a networked system that lets authorities search 46 million sets of prints within minutes. Analysts previously had to sort through two football fields' worth of file cabinets to compare prints. InArizona the fingerprints of illegal border crossers are checked against a Department of Homeland Security database (above) and against the FBI database. Future tracking may be done with irises: Their more complex patterns leave less room for error. Already, at Amsterdam's Schiphol airport (below), frequent fliers can save time with a program that stores their iris patterns on a card they can swipe.