Use of Various Casting Materials in Gelatin Block

The use of various firearms and tools to commit a crime is on the rise. Tool marks play a major role in cases where there is the involvement of weapons. Narrowing down such tools and comparing them help narrow down the type of weapon used. It is not always necessary that the tool/weapon be found at the Scene of Crime (SoC). In such cases, the only evidence to link the weapon is by documenting the wounding phenomenon. Gelatin block helps to measure bullet penetration, deformation, fragmentation and even the path of the projectile. This makes an ideal model in forensic science to study wound ballistics parameters. While examining the injury, it becomes important for investigators to narrow down the possible types of tools used in the crime. Photographs are taken for the same purpose; however, there are a few disadvantages concerning photography techniques. Using photographs, proper comparison is not always possible, as in terms of the curved surface, only one side measurement is accurate. Moreover, while photographing the impression, different lighting techniques are used, which may obscure the marks. Casting, therefore, has more importance and is advantageous over photography since casting can be used in the long run and remains a permanent record. It can last while the body is undergoing post-mortem and decomposition. Thus, the casting technique allows one to positively identify the weapon used even after several years. This study aims to make a cast of the cavity formed using various casting materials like Plaster of Paris, dental stone and alginate, which would make the comparison easier. It was found that alginate tends to clump very quickly, and Plaster of Paris and dental stone did not form a cast due to various associated factors.