A High-Tech Dragnet

When children disappear, a fate that has befallen 4,500 American kids in the past year, their faces usually turn up as blurry black-and-white snapshots tacked plaintively on poles around their neighborhood. But the crisp likeness of Polly Klaas, the 12-year-old girl who was kidnapped Oct. 1 from her home in Petaluma, California, has shown up everywhere: on television, on computer networks and on flyers in supermarkets, libraries and hospitals. The explanation for the ubiquity of the girl's image extends beyond a fascination with the brazen nature of the abduction: a knife-wielding bearded stranger intruded on Polly's slumber party. It even transcends...