EVERY batch of paper has a characteristic chemical fingerprint that could soon help to solve crimes as diverse as kidnapping, counterfeiting and fraud, say Australian researchers.

Crime investigations sometimes hinge on identifying the source of paper used for a ransom note, say, or to alter a business contract. But standard forensic methods often fail to do this with white office paper, which is the commonest type.

Now John Byrne of the University of Technology in Sydney and Lindsay Spence of the Queensland Police Service in Brisbane have come up with a rapid way of telling different white papers apart, using mass spectrometry to measure the trace elements they contain.

"It's only a small study, but they have an exceptionally high level of discrimination," says forensic scientist Chris Lennard of the Australian Federal Police in Canberra. Normally, a forensic scientist who wants to match two sheets of paper has to examine ...