Each person has their own unique gait, or gait signature, as it's also called. And when a criminal is caught on video, an expert in forensic gait analysis may be able to help identify the suspect by analyzing their walk. Deidre Seiden spoke to the first forensic gait analyst, forensic podiatrist Haydn Kelly, in London, England.
What is forensic gait analysis?
A person's gait is the style or manner in which a person walks. This involves movements from the head to the feet. So to put it simply, forensic gait analysis is the application of gait analysis knowledge to legal matters.
How did you become the first forensic gait analyst?
I was brought in as an expert in the case of R v. Saunders back in 2000. The enquiry came from the Metropolitan Police in London as to whether or not gait analysis could be carried out on the closed circuit television (CCTV) footage of the unidentified persons involved in robberies and comparing this to video footage of the known suspects. The trial received widespread media coverage at the time in the United Kingdom and elsewhere, including the front page of The Independent.
You provided expert evidence for a case here in Canada. Can you provide some details?
Yes, the first occasion of forensic podiatric evidence being led before the criminal courts in Canada was in the matter of R v. Aitken in 2009. The Victoria Police Department contacted me with an enquiry to examine video footage of a shooting and whether gait analysis could be helpful. I assessed the material and then analyzed it, and provided a forensic gait analysis report. The report was submitted as evidence by the prosecution and expert testimony was also given at the trial, which included rigorous cross-examination. The outcome of the trial was successful for the prosecution and the defendant was convicted by the jury of first-degree murder. The conviction was upheld following appeals.
What are you looking for?
Initially, I view the CCTV or unknown footage and then I observe the known footage of the suspect. I'm observing the person's gait and features of the person's gait for anything unusual. It's crucial the unknown footage is examined before the known footage as this process avoids confirmation bias. Comparisons are then carried out for both similarity and dissimilarity.
How does this help with investigations and in court?
Most, if not all, cases involve more than one piece of evidence and forensic gait analysis is one part of the forensic tool box. It may be useful in investigations when helping to locate a perpetrator. Or it can be used for evidential purposes when comparing the unknown person on the CCTV footage to custody footage of a known suspect.
Is there special training for it?
There is. Forensic gait analysis is a specialist area within the broader area of forensic podiatry, which also looks at barefoot prints and shoe prints. Forensic podiatry also covers the area where a person's podiatry records can be of use in disaster victim identification.
Not only do you need a podiatry degree, with a good understanding and experience of clinical gait analysis, but also experience of medico-legal casework so you have an appreciation of what the legal arena requires of an expert. Having this understanding is paramount, and anyone interested in the field should take post-graduate courses on report writing, cross examination, courtroom skills and law and procedure.
I'm currently working on the first textbook of forensic gait analysis that's due for publication this year.
What do you say to the skeptics?
All forms of identification are based on probability and forensic gait analysis is no different. Forensic gait analysis has been repeatedly tested in the courts and is shown to be a reliable tool. The use of DNA evidence is a super example of how something has moved on since it was first successfully used in identification, now 30 years ago. Development brings advancement and new ways to do things. Recognizing how and where that suitably fits into being helpful to existing systems is what's of value.