Footprint expert finds thieves' Achilles heel

A footprint expert at Queen Margaret University College in Edinburgh is hot on the heels of criminals with his research into forensic podiatry.

William Kerr is one of the few UK specialists who studies footprints and ridges on toes and soles of the feet, and is developing the science so that it can be used to provide evidence in legal proceedings.

It has been possible for some time to tell a person's height from a footprint. But Mr Kerr has produced an equation based on foot length and the area covered by aspects of the print to calculate weight. He says it is accurate to within 2kg to 3kg.

Mr Kerr has worked with a range of experts, including a Federal Bureau of Investigation agent who revealed the FBI's technique to lift tyre prints.

Mr Kerr uses similar means to lift footprints.

"No two footprints in the world will have the same shape and the right foot is always different from the left - there is never a mirror image," Mr Kerr said. "The ridge patterns on certain areas of the feet are as identifiable as fingerprints and that's why footprinting is just as interesting and exacting a science as fingerprinting."

Forensic podiatry is already a well-used police tool in countries where many people go barefoot, but Mr Kerr's research also highlights cases in the UK that have been solved using footprints.

One housebreaker, who wore gloves to avoid fingerprints, was caught because he removed his shoes to tiptoe round the house. A hole in his sock meant he was identified by a toeprint.

Another housebreaker had previously been convicted by fingerprints and impressions left by his trainers. On his next break-in, he removed his trainers and put his socks on his hands as gloves. He left behind toe impressions that led to two years' imprisonment.

Mr Kerr's research will be published in January.