processed food makes a fingerprint come up more clearly

http://www.sciencedaily.com/releases/2008/09/080915210509.htm

Dr. John Bond is a scientific support officer at Northamptonshire Police, and a researcher at the University of Leicester. Dr. Bond recently discovered that processed food makes a fingerprint come up more clearly. Dr. Bond described in a conference at the University of Leicester that when a criminal has eaten food that has a high salt content, their fingerprints make more of an impression. He said these clearer fingerprints will help to tell more about the person who left the mark. Bond has discovered this new method which allows scientists to ‘visualise fingerprints’.

The idea is that the fingerprints on a metal bullet shell appear more clearly when a sweaty finger touches it. Even after the bullet has been fired, this technique will make it easier for the scientists to analyze the prints. Dr Bond said, “On the basis that processed foods tend to be high in salt as a preservative, the body needs to excrete excess salt which comes out as sweat through the pores in our fingers. Dr. Bond and a group of scientists are now working on creating a scope that can detect the sweat itself, which could allow them to identify the type of person who left the sweat. This new process of studying the fingerprints on bullet shells isn't the best way to determine who committed the crime, but it is something for the police to use when they've got nothing else. The fingerprint would allow scientists to determine more about the type of person who committed the crime, but not actually be able to identify the single person.