Grease is the word

According to Dr Sue Jickells, “You are what you ingest”. And this is the key to a new forensic fingerprinting technique she and her team of scientists are developing. They call the process ‘Lifestyle Intelligence’ or ‘Intelligent Fingerprinting’

This method will give police forces a clearer profile of a criminal because they will be able to discover whether he or she uses drugs, smokes or even eats certain foods. 

This evidence can be extracted from tiny traces of sweat and grease that are left behind in the residue of a fingerprint.

Metabolites and antigens

Dr Jickells and her team are based in the department of Forensic Science and Drug Monitoring at King College, London. They are working alongside colleagues at the University of East Anglia in Norwich on this government funded project.

“This is a totally different way of looking at the fingerprint and the evidence it leaves behind,” she says. “Our system won’t replace the current methods. It will work in conjunction with them to provide a whole new layer of evidence.”

Dr Jickells’ system doesn’t examine the intricate patterns of crossovers, islands, deltas and ridge endings on a fingerprint. Instead it analyses “tell tale” deposits in traces of sweat the owner of a print leaves on a surface.

In these deposits are antigens. These are produced when the body breaks down substances such as toxins.

A vast amount of substances which you put into your system will come out through your skin. An extreme example would be eating garlic – a few hours later you can smell it on your body – particularly your hands and fingers.

The same is true for substances criminal investigation officers would be interested in, like cocaine, heroin, cannabis and even caffeine and nicotine.

The body treats a class A drug as a toxin and once it is in someone’s blood system it will try to get rid of it. It does this through a metabolic process which attempts to break the toxin down into a soluble antigen and pass it out of the system through the kidneys in urine. However, because those toxins have been suspended in a water based solution they will also come out in sweat.

If you can identify the antigens in fingerprint sweat you can then identify the original toxin or drug they came from.

“These sweat droplets in a fingerprint will contain a whole range of antigens which provide clues to its owner’s lifestyle,” says Dr Jickells. The palm of the hand and the fingertips provide us with a vast array of information because they are packed with ecrine glands and are almost constantly exuding sweat.

“Any police officer who is trained to examine a fingerprint will also be familiar with the sight of thousands of sweat pores tucked in between the ridges of that print.”

The detection process

The other half of this research team is based at the University of East Anglia and is headed by the Professor of chemistry, David Russell. He says the breakthrough came when the researchers were able to identify Cotinine – which is the antigen of nicotine – in a fingerprint sample.

Professor Russell explained to Police Professional: “If you smoke, your body breaks down nicotine to produce Cotinine. The Intelligent Fingerprinting team has developed a process where the antibody to Cotinine is suspended in a special solution and then applied to a fingerprint. If that fingerprint belongs to someone who smokes then the presence of the Cotinine will then be detected under a fluorescent light source.

“Once we had managed to highlight Cotinine we knew we could do something similar for virtually anything that was found in sweat. We have now managed to do the same with cocaine and caffeine.

“The first part of the process is a little like finding a key to fit a lock. If you ‘wash’ the antigen in the print sample with its laboratory produced antibody they bond together or inte