Computer programme to help witnesses remember criminals

London, Nov 30 ( Criminals are having a harder time hiding themselves, thanks to new software that helps witnesses recreate images and recognise suspects relying on principles borrowed from the fields of optics and genetics.

The software, known as EFIT-V system, is being used by 15 police departments in Britain, France and Switzerland. In field trials, it led to twice as many identifications of suspects as traditional methods.

Law enforcement agencies worldwide traditionally employ sketch artists. 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.

Christopher Solomon of the University of Kent in Canterbury, who developed the software, said the problem with this approach 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,” says Solomon.

His software generates its own faces that progressively evolve to match the witness’ memories.

The witness starts with a general description such as “I remember 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,” says Solomon.

The mathematics underlying the software is borrowed from Solomon’s experience using optics to image turbulence in the atmosphere in the 1990s.

One advantage of this technique, says 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 EFIT-V system proved to be quite effective even when witnesses say they can’t describe a person,” says Solomon.

The software has now started to make its way to the US, where it being used by researchers in university settings, says a Kent University release.

These findings were presented at the Optical Society’s (OSA) Annual Meeting, Frontiers in Optics (FiO), in San Jose, California.