Forensic calling cards
From Sherlock Holmes to Hannibal Lecter, people have loved the idea that the fingerprint would solve the crime. Thanks to the glands that secrete fatty substances from the fingertips, humans leave an easy-to-read calling card on almost every object they touch.

With advances in DNA technology, are the days of the crime officer collecting ‘dabs’ with a dusting brush and a piece of sticky tape numbered? Not yet anyway. Researchers at King's College London are uncovering the ways fingerprints are changed by age, smoking, drug use and even personal grooming products.

Personal revelations
Led by Dr Sue Jickells, Lecturer in Forensic Science and Drug Monitoring, the research into fingerprint chemistry is fuelled by the need to get better fingerprint images than those provided by the traditional dusted latent prints. They are developing a picture based on the understanding of chemical changes that occur in fingerprint secretions over time. Dr Jickells explains, ‘If you know something about the changes that are going on and the new chemicals that are formed then you can actually develop visualisation techniques that target them’.

Analysis of the fatty acids and other chemicals secreted via our skin can reveal details of our personal lifestyles. She describes one example, ‘We found a particular fatty acid that we had never seen before in anybody’s fingerprint secretion. When we went back to that person and said, “We found this, have you been using anything unusual?”, they had been using a particular hair product based on castor oil and that linked in with the fatty acid that was derived from castor oil’.

The bigger picture
These findings extend to particular drugs a subject might be consuming. Dr Jickells describes this process, 'If they can pick up drug use from sweat patches then we could pick them up in fingerprints. By comparing prints of smokers and non-smokers, we’ve shown that we can differentiate and pick up nicotine and its metabolised substance, cotinine and levels of that are higher in smokers than non-smokers. We’re about to go on and look at drug addicts and see if we can detect secreted by-products’.

Their research aims to develop sensitivity to a greater range of chemical substances in our fingerprints. Eventually we could even have the choice of giving a fingerprint rather than a blood sample to our doctor.