Software helps to spot criminals

Criminals are having a harder time hiding their faces, thanks to new software developed at Kent University that can help witnesses recreate and recognise suspects.

The software is already being used by approximately 15 police departments in the UK and by a half dozen European countries, including France and Switzerland. In field trials conducted by the Derbyshire police force, it led to twice as many identifications of suspects as traditional methods.

Law enforcement agencies around the world traditionally employ sketch artists, who piece together faces in a process similar to assembling a Mr Potato Head toy. The witness describes key features - such as hair length, nose size or sharpness of the chin - and the artist combines them to create a likeness. Some departments now have computer programs that follow the same approach as these artists, creating facial composites using databases of pre-drawn features.

The problem with this approach, said Kent University researcher Christopher Solomon, is that it doesn’t take into account how the memory actually works. ‘There’s quite a bit of research in the psychology field suggesting that we’re not so good at this, at recalling and describing a face,’ added Solomon.

His software generates its own faces that progressively evolve to match the memories of the witness. The witness starts with a general description such as ‘a young white male with dark hair’. Nine different computer-generated faces that roughly fit the description are generated, and the witness identifies the best and worst matches. The software uses the best fit as a template to automatically generate nine new faces with slightly tweaked features, based on what it learned from the rejected faces.

‘Over a number of generations, the computer can learn what face you’re looking for,’ said Solomon.

One advantage of the technique, added Solomon, is that it can be used on witnesses who can’t recall details about a suspect but say that they would remember the face if they saw it again. Traditionally, police sketch artists cannot work with these people. By tapping into recognition instead of recall, the so-called EFIT-V software proved to be quite effective even when witnesses say they can’t describe a person, according to Solomon.

The software has now started to make its way to the US, where it is being used by researchers in university settings. In the future, Solomon hopes to partner with a suitable US company and market the technology to police departments.