It is important to note that footprint and firearm evidence can be highly useful in identifying and narrowing the pool of suspects. In the case of the former, footwear leaves an impression, which needs to be photographed and cast procedurally in order to ensure its future use for examinations. Firearms leave gunpowder, shells, and other critical pieces of evidence, which can be utilized with the same purpose of identification.
Firstly, a footprint or footwear evidence can vary in its usefulness depending on the number of details provided by it. It is stated that “individual footprints are generally preserved only if they contain details of value for identification” (Fisher & Fisher, 2022a, p. 132). The greatest degree of value is offered by repair marks, irregularly placed pegs, nail marks, injuries, characteristic fittings, and signs of wear. However, the shape and size of a shoe, as well as its pattern, offer lower evidential value. Footprints on the snow with frozen crusts are the most useless form of evidence since it does not reproduce shoe details (Fisher & Fisher, 2022a). In order to preserve the evidence, the area should be cordoned off and the footprint covered with a box.
Any destruction or alteration must be stopped, and preservation done either by casting or photographing. Photographing should be done with a tripod placed vertically above the footprint and aimed perpendicularly at the impression. One should additionally put a ruler or scale near the impression in order to a reference. The lighting should be sunlight, but if it is cloudy or dark, artificial light should be used. In addition, the lighting should be oblique in order to create shadows and highlights since impressions are three-dimensional. Alternatively, casting can be done with dental stone as well as other materials, such as silicone rubber, sulfur, or paraffin (Fisher & Fisher, 2022a).
Dental stone is the best choice for its wide usability and availability, and it can be used in water-filled impressions without the removal of water. No special preparations are necessary for the earth, dry sand, and loose soil footprints, whereas snow impressions need Snow Print Wax spray before applying the dental stone.
Secondly, when it comes to the procedures used in the examination of firearms evidence, its destruction should be minimized as well. It is important to mark and measure the locations of shotgun shot patterns, bullet fragments, bullets, bullet holes, and cartridge casings (Fisher & Fisher, 2022b). In the case of a weapon being found at the crime scene, its removal must be postponed until all the measurements are taken, photographed, sketched, and 3-D scanned (Ott et al., 2017).
Fingerprints on the weapon must be handled properly by an investigator, and if it is held, then the grip and weapon position are of critical importance as well. After the removal of the firearm, it should undergo a preliminary examination with every detail found written down with precision. The type of a gun is critical since its functional elements can provide additional information. Bullet and cartridge types can be useful for analysis since they leave specific markings and holes depending on the surface. One should use and consult the National Integrated Ballistic Information Network (NIBIN) to compare images with the ones on the database.
In conclusion, a footprint or footwear evidence can vary in its usefulness depending on the number of details provided by it. Any form of destruction or alteration of the impression must be stopped, and preservation should be done either by casting or photographing. For firearms, one must mark and measure the locations of shotgun shot patterns, bullet fragments, bullets, bullet holes, and cartridge casings. Weapons themselves must be handled with greater care and precaution due to additional evidence as well as safety.
References
Fisher, B. A. J., & Fisher, D. R. (2022a). Chapter 9 impression evidence. In B. A. J. Fisher & D. R. Fisher (Eds.), Techniques of crime scene investigation (pp. 129-142). CRC Press.
Fisher, B. A. J., & Fisher, D. R. (2022b). Chapter 10 firearm examination. In B. A. J. Fisher & D. R. Fisher (Eds.), Techniques of crime scene investigation (pp. 143-164). CRC Press.
Ott, D., Thompson, R., & Song, J. (2017). Applying 3D measurements and computer matching algorithms to two firearm examination proficiency tests. Forensic Science International, 271, 98-106. Web.