A new way of detecting and visualizing fingerprints from crime scenes using color-changing fluorescent films could lead to higher confidence identifications from latent (hidden) fingerprints on knives, guns, bullet casings and other metal surfaces. The technique is the result of a collaboration between the Univ. of Leicester, the Institut Laue-Langevin and the STFC’s ISIS pulsed neutron and muon source, and will be presented today at the Royal Society of Chemistry’s Faraday Discussion in Durham.
When your finger touches a surface, it leaves behind deposits of sweat and natural oils in a pattern that mirrors the ridges and troughs found on your fingertips. The odds of two individuals having identical fingerprints are 64 billion to 1, making them an ideal tool for identification in criminal investigations.The greatest source of fingerprint forensic evidence comes from latent fingerprints, i.e. those not immediately visible to the eye, because they are less likely to be ‘wiped’. However, visualizing these prints with sufficient clarity for positive identification often proves difficult. Despite the availability of several enhancement techniques, only 10 percent of fingerprints taken from crime scenes are of sufficient quality to be used in court.The classical approach to enhance latent print visibility is to apply a coloured powder that adheres to the sticky residue and provides a visual contrast to the underlying surface. However, these techniques require significant preservation of fingerprint material and are therefore vulnerable to ageing, environmental exposure or attempted washing of the fingerprint residue.