Science steps up

Criminals may avoid leaving fingerprints by using gloves but they can’t avoid leaving tell-tale impressions of what they are wearing on their feet.

This, coupled with a change in the law which enables the police to demand impressions of footwear from suspects, is why shoeprints are suddenly of great interest to police and forensic scientists.

Work just starting at the University of Sheffield will examine how automated computer systems could help the police search and match shoeprints in order to link suspects to crime scenes.

“In some ways shoeprints are the forgotten part of forensic science,” comments Professor Nigel Allinson who is leading the EPSRC-funded study, “but while they aren’t as unique as, say, DNA evidence they are often present at the scene.”

Currently the task of matching an impression to a suspect’s shoes is laborious and difficult.

Many of the problems relate to the evidence itself, as it often consists of partial impressions such as toe scuff marks on a door or faint heel impressions on a carpet. A variety of techniques are used to capture this evidence including photography, gels, powders and even that movie stalwart the plaster cast: making for poor quality images for comparison purposes.

While there are databases of thousands of ‘outsole’ patterns (which is regularly updated with new footwear) this can only be annotated and then searched manually “you might search for ‘three circles together’ but unless other operators have interpreted the pattern in the same way and used the same annotation you won’t find it,” comments Professor Allinson.

His long-term goal is to fully automate the process of matching shoeprints to a similar level as that now employed for fingerprints.

This new project is only the first step towards a fully automated national system. “We need to develop a good idea of what techniques to use and the different elements that police and forensic scientists need,” says Professor Allinson, “this isn’t always obvious from the outset, so we have to spend time talking to everyone involved.” A lot of their efforts will focus on developing common descriptions and standards that will work across all the police forces in the UK.

Once this feasibility study is complete they hope to go on to create a system which will identify the type of shoe from a shoeprint and then match it to a suspect’s footwear reliably enough for it to be used in court. Professor Allinson concludes: “In the future this could be integrated into Ident 1, the system currently used to catalogue and match fingerprint, palm and DNA evidence.”

Reproduced by kind permission of the Editors of Newsline, an EPSRC publication.

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