Because forensic science is based on physical evidence, forensic investigators analyse crime sites or crime scenes for physical evidence like fingerprints, blood, lip print, Footprint, etc., in order to identify the perpetrator and solve crimes. Fingerprint is a very important piece of evidence so is Footprint. The footprint is an important piece of physical evidence found at many crime scenes, including homicide, burglary, and sexual assault, yet it is often overlooked in the early stages of an investigation. The most crucial aspect is the inspection and comparison of footprint impressions. These are subjected to a thorough forensic scientific assessment. Footprints may reveal information that can aid in the identification of a suspect and the crime scene. The stride dimension, location of each footprint, its shape, size, angulations and depth, interspaces and outer margins, heel creases, injuries or accidental damages provide indirect information about gait pattern, person’s height, leg length, range of body weight, and interrelated movement of the foot, ankle, leg, and body that are unique to that person.
At one Florida case, for example, a bloody shoe print was discovered on the carpet in the house of a murder victim. The print suggested that the impression was caused by a hole in the shoe. Investigators gathered and tested shoe prints from people who were known to be at the area near the time of the murder. By superimposing the bloody shoeprint from the crime scene with the test print made from the suspect’s shoe, footwear examiners were able to identify the culprit.
The Impression of a Footprint can be divided into two categories.
- 2-D (Two Dimensional)
- 3-D (Three Dimensional)
When the underside of a shoe collides with a hard, flat, or plane surface, such as a tile floor or a concrete, this type of impression is created. The substance is frequently transmitted from the sole of the shoe to the ground. Those formed with moist dirt and blood, are known as positive impressions. A favourable impression is usually obvious. These are formed in the dust or on a surface that has been lightly waxed.
These forms of footprint impressions occur when a shoe is impressed into a soft material such as mud, sand or snow.
Collection of Footprints:
General photographs showing the evidence position in relation to the rest of the scene, as well as high-resolution images of the individual imprints or impressions, are taken in the instance of impression evidence. Examiners may use other light sources or chemical enhancers to capture as much detail as possible, particularly when dealing with latent imprints. 35mm SLR is considered as best camera.
Examiners should utilise the least destructive procedure initially when lifting impressions.
Electrostatic Dust Lifter
Electrostatic lifting is beneficial for detecting and lifting dry origin dust and residue impressions caused by tracking from dry unclean surfaces to relatively cleaner surfaces. There are several electrostatic lifters on the market. All of these gadgets make use of a film with a black and an aluminum coated side. The black side of the film is put against the impression, and a high voltage charge is given to the film, causing the dry dust or residue impression to transfer.
Lifted impressions should be evaluated in a darkened area with a high intensity light source held at an oblique angle to the lift’s surface. Electrostatic lifts are delicate, and any swiping movement across the surface of the lift can erase the impressions. Lifts should be photographed before they are packed. Electrostatic lifts are chargeable and should never be packed in cardboard, cardboard boxes, or plastic bags.
Adhesive And Gelatin Lifters
Footwear size adhesive and gelatin lifters are used to lift dust and residue imprints, wet origin impressions, and fingerprint powder impressions.
Gelatin lifters come in white, black, and clear. White lifters provide more contrast when combined with dark coloured powders to enhance impressions. Black lifters contrast well with light coloured powders and residual impressions. Clear lifters do not generally give strong contrast. Photograph gelatin lifts of residue impressions as soon as possible after collecting.
Casting can capture any plastic or three-dimensional footwear or tyre impressions. Casting involves the use of a powdered stone substance, such as dental stone, that is combined with water and poured into the impression. When it dries, this process generates a three-dimensional model of the impression.
Enhancement of Footprints Photograph
Imprints and impressions can be enhanced or improved to bring out more minute details. A digital enhancement programme, such as Adobe Photoshop®, can be used to increase the quality of a photographed tyre track, for example. Fingerprint powders and chemical stains or dyes can improve image colour or contrast with the background. This allows evidence that has been lifted or cast to be photographed or scanned.
Evaluation and Comparison
Every footmark has an individual entity that cannot be duplicated.
Examiners employ instruments such as dividers, callipers, special lighting, and low magnification throughout the examination and comparison. Examiners evaluate the different parts of the tread design, as well as the length and width of the impressions, and then compare those dimensions to what is visible in the crime scene print or impressions. Low magnification and specific lighting are sometimes used to assess whether certain qualities are incidental or a result of the production process. Examiners conduct side-by-side comparisons by placing the known shoe or footprints alongside the crime scene print to analyse related areas. Many features for identifying traits, Cycling toes, long and short toes, missing toes, partially chopped toes, and injured toes can all provide useful traits and may be adequate for identification. The phalange of the toes creates phalange markings; their existence, position, forms, and sizes are frequently identifiable qualities. They are usually encountered in the foot mark. Because it contains multiple identifying features, it is feasible to identify a footwear mark even if it is incomplete. Heel markings alone can occasionally identify a shoe. The most significant evaluation of a footprint is the identification of a gate pattern for the direction line, the walk line, the foot line, the foot angle, the step angle, and so on.