It is a fact that most of crimes involve weapons (firearm or tool). The concept of individuality (as applied to the fingerprints and DNA of humans) is also applicable in case of firearms. Certain striations and markings are left on cartridges and bullets when fired by a weapon. These markings are unique and belong to that particular weapon thus making it “fingerprint” of the weapon. Likewise, the striations and indentations left on a surface or object by a tool are unique identification marks of that particular tool. The firearm and tool marks analysis is thus based on this fundamental principle of individuality. Firearms and tool marks lab of NFSA started to work in 2013 and since then providing various services including:
- These include comparison of cartridge with cartridge, cartridge with weapon, bullet with weapon and bullet with bullet. Cartridge with cartridge comparison is done to know whether fired cartridges recovered from a place of occurrence had been fired from a single weapon or multiple weapons. Cartridge with weapon and bullet with weapon comparisons are done to determine whether the cartridge/bullet has been fired from that particular weapon or otherwise. Test fires are done with the suspected weapon consequent upon which the test empties/bullets are compared with the crime scene cartridges/bullets.
- Workability of the weapon
- This is done to determine whether a weapon is mechanically in working condition or otherwise. This helps in cases where accidental shots are involved.
- Bullet trajectory analysis
- This is done to backtrack the direction, speed, calibre of weapon and approximate distance of fire on different exhibits.
- Gunshot Residue(GSR) Detection and Analysis
- GSR is the analysis of unburnt residues of gunpowder. This test is done for two purposes namely shooter determination and approximate distance determination (in close shots only). Shooter can be determined by examination of hands of shooter. Approximate distance through GSR analysis is done from clothing of the victim. Test fires are done on similar clothing for comparison.
- Tool marks Identification and Comparison
- This is important in investigations involving burglary and theft cases. Certain markings are left behind on items where tool have been used. Exhibit bearing tool marks may be sent for comparison with the
- tool recovered to ascertain whether the same had been used or otherwise. If it is not possible to transport the exhibit, silicon moulds may be made and sent to lab for comparison.
- Serial number restoration on firearms and vehiclesSerial number on metal frames are embossed by the manufacturer. Any attempt of erasing, obliteration, self-punching or cut/weld can be detected by application of certain tests. Such type of analysis is done on serial number of weapons. This is also applied to check the veracity of engine number/chassis number of vehicles.