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Evolving the Face of a Criminal

Publication date: Feb 11, 2013 01:41 PM

Start: Jan 31, 2012 12:00 AM

Dr. Charlie Frowd, University of Central Lancashire.

EvoFIT is a software system that helps victims and witnesses of crime generate an image of a criminal’s face. It draws on Dr Frowd’s research looking at techniques to improve the effectiveness of facial composites, so that eyewitnesses can build a clearer, more accurate image of the person they saw commit a crime. The pioneering system requires witnesses and victims to repeatedly select from screens of complete faces, with ‘breeding’, to ‘evolve’ a composite of the criminal’s face. It is currently used in crime investigations throughout the world because of the high identification rate of its composites.

EvoFIT composites have been made even more effective with a novel animation technique that Dr Frowd has developed.  The technique progressively caricatures a composite, similar to the way sketch artists work, exaggerating characteristic parts of the face.  Police can use this image format when making public appeals for information on TV and online newspapers, substantially increasing the chances of identifying the criminal.

Background to the work

Dr Frowd’s research explored the effectiveness of traditional methods for constructing composites using software programs in current police use. Such systems build a face by witnesses and victims selecting individual facial parts: hair, eyes, nose, mouth, etc. The research has found a startling result: a composite is rarely named correctly when constructed a couple of days after the face had been seen, the norm for witnesses and victims of crime. As a consequence, and part of collaborative research, Charlie has initiated and led a range of projects that have sought to improve the quality and recognition of these images. He has also about 40 research papers published in the field.

Charlie’s PhD in Stirling involved development of a new composite system. It is called EvoFIT and was inspired by how we perceive human faces, as whole entities, and also by selection and breeding processes that are found in nature. EvoFIT presents users with sets of complete faces and they
select a few that resemble the criminal. The software then breeds these faces together to produce more faces. While the faces at the start have random characteristics, repeating the selection and breeding process a few times allows the system to converge on a specific identity. Using
procedures that mirror policework as far as possible, the latest version of EvoFIT now evolves a face that can be correctly named 45% of the time when constructed following a two day delay. EvoFIT is in use in a dozen police forces across the UK and abroad, and reports from the police indicate a
success (arrest) rate in the region of 50%.

While EvoFIT has led to significant improvements in facial identification, it has always been difficult to get a good-enough image to reproduce in newsprint. However, Dr Frowd’s team have experimented with “stretching” the faces and getting people to look at them sideways on, rather than looking straight at the image in front of them.

In testing, people were twice as likely to correctly identify a composite when it was stretched and turned sideways (36%) as opposed to when they viewed them normally (17%).

Dr Charlie Frowd is based in the School of Psychology at the University of Central Lancashire, Preston. He started his academic career twelve years ago at the University of Stirling, in Scotland, where he completed his PhD in Psychology and then worked on a series of government-funded grants with Vicki Bruce and Peter Hancock. Two years ago, he joined the School of Psychology at UCLan and is now a senior lecturer. His main research interest is in the area of police facial composites (pictures of suspects to crime, as seen in the newspapers and on TV crime programmes).

charlie frowd