Computers: Cash-Machine Magician

Automated bank-teller machines can be maddening devices, but there is one thing they supposedly do well: protect customers' accounts. Not always, apparently. Police are looking hard for Robert Post, 35, a Polish-born electronics expert and former ATM repairman who brags that he is something of a magician. According to the Secret Service, Post last year managed to make some $86,000 disappear from cash machines -- all from other people's bank accounts.

Post allegedly worked his legerdemain with blank white plastic cards and a small magnetic encoding machine that he bought for $1,800. By peering over customers' shoulders and retrieving their discarded...