A Camera That Reads Writing After It Has Been Erased

The U. S. Postal Inspection Service boasts that it convicts a higher proportion of arrested suspects than any other federal crimefighting agency, including the FBI. One reason is the agency's high-tech crime lab in Washington.

Among the lab's newest weapons is an infrared video imaging system that can often reconstruct otherwise undetectable evidence. Recently, for example, a thief signed a credit card he had snatched from a mailbox. After using the card for a few days, he sponged off the signature, then threw the card away. But it was retrieved and the system detected the signature from invisible ink residues. A handwriting expert's testimony then helped convict the crook. Unlike conventional IR film, the video system allows details to be computer-enhanced before the image is printed on a high-resolution printer from Lasertechnics Inc. in Albuquerque.

Before it's here, it's on the Bloomberg Terminal.