12.2: Footprints
- Page ID
- 53151
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Footwear analysis is an interesting discipline of the forensic sciences. Valuable information is often obtainable from the analysis of footwear impressions left in a crime scene. Footwear impressions can provide class characteristics (brand, outsole pattern, and size) as well as individual characteristics if the impression contains good detail and clarity. Unfortunately, footwear impressions are generally the first item of evidence destroyed by responding officers and emergency medical personnel. That is why it is essential for the forensic technician to get to the scene as quickly as possible.
We can separate footwear analysis into three groups:
- Gait analysis
- Footwear impressions analysis
- Analysis of footwear
When measuring the gait of an individual the stride is the linear distance from the heel-strike of the same foot. The step is the distance between successive points of foot-to-foot contact of alternate feet. In normal walking, the distance between heel strikes of each opposing foot is a step and that of the same foot, a stride. The angle formed between each foot and the line of progression is the angle of gait. This type of information can be useful at the crime scene to assist in proving direction and participation of an individual, and may, with the appropriate analysis, provide information independently establishing the identity of the suspect.
‘Where pathological changes occur in the foot and lower limb, obvious changes in step, stride, angle of gait can occur. Forensic podiatrists can interpret such changes, which can have value in the forensic interpretation of sequences of footprints and in observing any deliberate attempts to alter gait during the collection of suspect footprints.’ (Wesley Vernon, 1998)
Podiatry is a clinical profession with a focus on the foot and its disorders. Forensic Podiatry is the development and application of sound podiatric knowledge in a forensic context.
The potential areas of use include:
- Identification from podiatry records
- Biomechanical assessment of gait
- Barefoot pattern interpretation and analysis
- Footwear interpretation and analysis
Furthermore, footwear impressions can assist the analyst in determining the participation of suspects, witnesses, and victims; including the direction of travel and the speed (walking or running) they entered or exited. In our walking process, the deepest impressions will usually be at the toe and heel ends, with a slight elevation near the arch of the foot. In the running process, the action is usually in the toe area, with the toes digging in, followed by a backward kick; the heel is not usually as pronounced as the toes. A person walking in a backwards motion will have their strides shorter than in normal walking. Toes dig in as in running, but heel points will be more distinct than those found in running. The short steps occur from the structure of the leg muscles and an uncertainty as to just where the foot is being placed. An individual’s gait pattern is relative to that person’s physical qualities.
Your author investigated a crime scene that was in a dirt area between a building and railroad tracks. The deceased victim remained in the crime scene with a gunshot wound to the chest and another to the head. Your author detected two sets of footwear impressions that indicated two persons entered the dirt area walking side-by-side at first, followed by two sets of footwear impressions reflecting one person was being chased by the other. Finally, both footwear impressions doubled back to the area where the decedent lie that indicated a short scuffle ensued before the victim was shot in the chest. He was shot in the head after he fell to the ground. One set of footwear impressions indicated the direction of egress by the suspect. Since the victim was still wearing his shoes, it was easy to determine who was being chased by whom.