New study that will make criminals sweat

Researchers have discovered that individuals whose diet is high in processed foods are more likely to be discovered by police through their fingerprint sweat corroding metal.

It follows a previous breakthrough study into the way fingerprints corrode metal surfaces such as gun cartridges.

Dr John Bond, a researcher at the University of Leicester and scientific support manager at Northamptonshire Police, said processed food fans are more likely to leave tell-tale signs at a crime scene due to a high concentration of salt in their fingerprints.

His team has developed a method that enables scientists to visualise fingerprints even after the print itself has been removed. He and colleagues conducted a study into the way fingerprints can corrode metal surfaces. The technique can enhance – after firing – a fingerprint that has been deposited on a small calibre metal cartridge case before it is fired.

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.

“So the sweaty fingerprint impression you leave when you touch a surface will be high in salt if you eat a lot of processed foods – the higher the salt, the better the corrosion of the metal.”

Dr Bond said there was scope to take his research further and to look at the constituents of sweat itself in order to profile an individual. “We are currently in talks with the University of Leicester to see if there is scope to investigate sweat itself and whether it can identify the type of person who left that sweat mark.

“Important for us is how the salt varies but there is potential to investigate other elements to describe the kind of person who left the mark.

“The implications this has for frontline investigations could become even more apparent as we begin to look for other lifestyle clues contained with a fingerprint such as age, ethnicity, sex and geography.

“It would give lifestyle information that, whilst nowhere near as good as identifying individuals with their fingerprints, it is still very good for police if they have got nothing else to go on.

“This would be particularly helpful for terrorist type crimes where the nature of the incident would tend to obliterate forensic evidence. So a sweat mark on a piece of metal or bomb fragment that might be recovered from an incident might be able to provide a clue to the type of person who perpetrated the incident.”

Dr Bond described the new study as a process of intelligent fingerprinting – using the fingerprint to tell investigators more about the individual rather than a simple identification.