by Michael S. Nirenberg, DPM | Oct. 7, 2024 | Footwear Impression
The Importance of Gait as Evidence
Gait, the manner that people walk, run or move from place to place is an often-overlooked piece of evidence—particularly when a criminal is “caught” on video. With increasing frequency gait is being used as supporting evidence for inclusion or exclusion of an individual as a suspect and ultimately, as a contributor to identification.
Gait as a Key to Aid in Identification on Surveillance Video
When CCTV footage or other surveillance video shows a criminal, the person’s gait may be important evidence, particularly when the perpetrator’s face cannot be seen or is outright hidden. For example, the criminal may wear a mask or their face may be obscured by a hat or hoodie, poor lighting or the result of the camera only capturing their backside. Even in cases where the investigator recognizes the criminal, gait can provide additional evidence, as the suspect to be shown the video and declare, “that’s not me.” While a jury may disagree, having an expert show that the suspect and criminal walk with the same gait or a different gait may help the jury reach their conclusion.
The Science of Forensic Gait Analysis
The use of gait analysis or gait comparison in criminal matters is referred to as forensic gait analysis. The science of forensic gait analysis is based on the premise that humans walk (and run) with distinctive, recurring features or characteristics. This variation in gait among persons may be the result of a multitude of factors, such as heredity, injury, body habitus, health issues, weight and/or other factors.
The Process and Tools of Forensic Gait Analysis
The process of forensic gait analysis involves a thorough evaluation of how an individual seen on video walks, considering major biomechanical motions, literally from head to foot. Through this process, a forensic podiatrist or gait expert creates a “picture” of the person’s gait. The methodology used by myself and other forensic scientists uses a gait tool to assist in the evaluation of a person’s gait. This tool, referred to as the Sheffield Gait Tool, has been researched, evaluated, peer-reviewed and published. The use of this gait tool by analysts has been shown to provide results that are valid, repeatable and scientifically sound.
Using Gait to Link Criminals Across Crime Scenes
Beyond showing that a criminal and suspect walk the same (or differently), gait can be used to assist in linking or unlinking a person to multiple crime scenes. This could be particularly useful if the criminal is wearing clothing that varies between locations and their face is not visible. This example emphasizes an important point: even if a criminal hides their face, they do not think to hide their gait. That is, while we can force ourselves to alter our gait (i.e. think of runway models), in practice this is not something most criminals have thought to do.
Gait as Supporting Evidence in Criminal Investigations
While gait in this context is not considered unique, it can provide important supporting evidence for inclusion or exclusion of a person as a suspect during an investigation, and also as supplemental evidence for trial. In the United Kingdom, the government’s Forensic Science Regulator published the Code of Practice for Forensic Gait Analysis, establishing forensic gait analysis as a recognized forensic specialty and providing recommended best practices on its application.
The Role of Video Cameras in Forensic Gait Analysis
The opportunity for law enforcement to use forensic gait analysis in criminal investigations is much greater these days due to the increased use of U.S. cities with surveillance cameras. A study conducted in July of 2022 determined that major U.S. cities had an average of 2,239 cameras for every 10,000 residents. The most surveilled city in the country is Atlanta with 50 cameras for every 1000 people. Plus, access to Ring doorbell camera footage has grown, and there are hundreds of police departments who have partnerships with Amazon’s home surveillance products. The Ring cameras have been referred to as the nation’s “new neighborhood watch.”
Ring Cameras and Expanded Surveillance
These types of partnerships allow the police to ask for the video from homeowners’ cameras. This helps them view footage from the company’s millions of Internet-connected cameras installed nationwide. Ring’s cameras can provide images of a front doorstep and neighboring homes across the street and down the block. This range can be expanded by installing the motion-detecting cameras along driveways, decks, and rooftops.
The Growing Presence of Surveillance Technology
In addition to this growth in video coverage across the U.S., there’s the pervasive presence of smartphones and the rise in the use of hobbyist or law enforcement drones which can provide “real time” images of crimes as they occur or reveal persons approaching or leaving a crime scene. As a result, there are more chances for video cameras to observe people’s conduct and more opportunities for their use by law enforcement.
Conclusion: The Future of Video and Gait Analysis in Criminal Investigations
The use of video as evidence in criminal matters is only going to grow, and with it, the need to assist in criminal investigations will also grow. Beyond clearly seeing a person’s face, investigators now have a potent, additional piece of evidence—forensic gait analysis—to assist them in their fight against crime.
Michael S. Nirenberg, DPM
Dr. Nirenberg is a clinical and forensic podiatrist who has assisted in the examination of footprints, footwear and gait in criminal matters with his expertise having been sought for cases in the U.S. and other countries. He is a co-editor of the textbook Forensic Gait Analysis: Principles and Practice, and has provided presentations to law enforcement, attorneys and forensic scientists. At the time of this writing, he is president of the American Society of Forensic Podiatry, serves on the editorial board of the noted forensic journal Science & Justice, serves on the General Forensics Science and Practice Subcommittee of the International Association for Identification and is the Chair of the Exploratory Task Group on Gait Analysis within the Organization of Scientific Area Committees (OSAC) for Forensic Science. He practices podiatric medicine in Crown Point, Indiana, and his email is: [email protected] or at https://www.friendlyfootcare.com/forensic-gait-analysis/