Identifying suspects by matching hand photographs with video evidence

Reports by minors of sexual relations against their will are not rare, and in some cases pornographic photography is a part of the abuse. Such material can be used to help identify the perpetrator. In this study we examined the efficacy of visual comparison between two databases. One consisted of blinded still images of the back of the right hand of 51 males from video recordings, the other of blinded high quality camera images of the back of the right hand from the same 51 individuals. The images were compared in pairs (2601 combinations) and a judgment was made about whether they were a highly likely, possible or unlikely match, using several anatomical features as markers for comparison. Using this method all 51 high quality images were correctly matched with the video image from the same person, though in some cases there was up to 5 other samples that could not be excluded as possible matches. In total there were no false positive "highly possible" matches, but there were 50 false positive "possible" matches. Visual comparison of the back of the hand is a valuable addition to the burden of evidence in a judicial setting, but should not be used as a standalone method to establish proof of identity. The applicability of the method is dependent on the existence of a database of images; the degree of certainty of the identification is directly correlated to the size of the database.