New Delhi: Law enforcement agencies the world over are resorting to gait analysis in investigations where closed-circuit TVs (CCTVs) have managed to capture the crime but not the face of the criminal. For instance, gait analysis was reportedly used by the Karnataka Police and Directorate of Forensic Sciences in Gujarat to confirm the identity of one of the culprits who shot journalist Gauri Lankesh in September 2017 in Bengaluru.

What is gait analysis?

Commonly used for clinical purposes, forensic gait analysis is a systematic study of how a person walks or runs (hence, “gait"). It involves a frame by frame examination of a person’s body (when they are moving) to identify a pattern called gait signature. To generate this signature, analysts take into account the person’s posture, length of strides, movement of hands, head tilt, distribution of weight and angle of feet during movement. Analysts compare the walking pattern of the culprit from the CCTV recording with that of the suspect, captured later. In the Lankesh murder case, police reportedly re-enacted the crime scene to match the movement of the shooter in the CCTV recording with that of the suspect.

Is it reliable?

Experts believe a person’s gait isn’t unique like a fingerprint, but it also differs from person to person. However, they don’t rule out that a careful examination of the walking style of a suspect with that of the criminal in the CCTV footage, by skilled observers, can nudge authorities in the right direction.

A 2013 study by Ivan Birch, leading forensic gait analyst and member of the UK-based Chartered Society of Forensic Sciences, published in the Science and Justice Journal, showed how experienced analysts were able to connect suspects with their scene of crime with an accuracy of 71%.

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