By day, Michael Nirenberg of Crown Point, Indiana is ‘America’s podiatristSM’, helping people treat warts, arthritis, ingrown toe nails, heel pain and all sorts of other foot problems. In his spare time, he helps the police solve murders.
For one case, a double homicide in Idaho, Nirenberg analyzed foot impressions left inside shoes that the suspect wore in jail. They matched those left at the crime scene. “The way you wear one pair of shoes, a lot of times, will carry over to your other shoes,” he told a local TV news reporter.
From the O.J. Simpson trial to the popularity of Nancy Grace and CSI, it’s clear that the public loves forensic science. We never tire of hearing about the justice system’s use of DNA screening, fingerprinting, fiber analyses, and even brain imaging. But when’s the last time you read about foot forensics? I got curious about it, and discovered that loads of information can come out of a humble footprint—whether left on the ground, a body or inside of a shoe.
Every foot is unique: from the delicate skin impressions across the sole, to the location of bunions, the alignment and length of the toes, and the distribution of weight across the ball, arch and heel. To the trained eye, a footprint can reveal the gender, height and weight of the person who left it, and sometimes even how they walk.
For example, two years ago in Lancashire, England, a house burglar was convicted thanks in part to grainy footage captured by a nearby surveillance camera. Although the tape didn’t catch the man’s face, podiatrist Ian Linane identified him by analyzing, frame by frame, his distinctive bow-legged gait.
The first recorded use of foot forensics dates to 1786, in Scotland, when a bootprint left next to the body of a little girl was matched to the boots of someone attending her funeral (yikes!). Yet only a few dozen forensic podiatrists are registered in the U.S. and the U.K. In fact, the world’s largest forensic science organization, the International Association for Identification, didn’t recognize forensic podiatry as an official discipline until 2008.
Two other types of specialists are known for analyzing foot patterns: footwear examiners, who focus on the wear and tear of shoes and the imprints that various models leave; and forensic anthropologists, who study human skeletal remains.
In contrast, forensic podiatrists take particular interest in the relationship between the foot and the shoe—information that can be crucial for solving a crime. For example, a 2006 review describes an investigation in which sneakers left at the crime scene were a size 8 and the suspect’s shoes were a size 7. A podiatrist determined, however, that the crime scene shoes were too big for the person who wore them, and that the foot impressions inside both sets of shoes were extremely similar.
In case you’re not yet convinced about the coolness of foot forensics, I’ll leave you with a few examples of the high-tech tools involved.
With a ‘force-plate’ system, a person stands (or jumps, or runs in place) on top of a sensitive metal plate that is connected to a computer. The set-up allows a podiatrist to see, in a colored heat map, precisely how weight is distributed across the foot.
When Nirenberg first started his detective work, he would use a dental mirror to examine the inside of a shoe, but would have to cut the shoe apart for closer inspection. One day, he was performing an ankle procedure with a fiberoptic camera and realized that this would be a much better way to peer inside of a shoe, with the added benefit of capturing footage for investigators and juries. He published the method in the May 2008 issue of the Journal of Forensic Identification.
All images courtesy of Michael Nirenberg.
Guest Blogger Profile: VIRGINIA HUGHES (web/Twitter) is a freelance science writer, Brooklynite, foodie and brain geek. Her articles have appeared in Discover, Nature, Popular Mechanics and The Scientist. She blogs at The Last Word on Nothing, NOVA’s Secret Life of Scientists & Engineers, and On SFARI. This week, she’s reporting on autism research from the Society for Neuroscience meeting.