Linescan imaging of ballistics projectile markings for identification

The identification of firearms from forensic ballistics specimens is an exacting and intensive activity performed by specialists with extensive experience. The introduction of imaging technology to assist the identification process of firearms has enhanced the ability of forensic ballisticians to conduct analyses of these specimens for identification. The characteristic markings on the cartridge and projectile of a bullet fired from a gun can be recognised as a fingerprint for identification of the firearm. Forensic ballistics imaging has the capacity to produce high-resolution digital images of cartridge cases and projectiles for matching of crime scene specimens to test specimens. Projectile bullets fired through the barrel of a gun will exhibit extremely fine striation markings, some of which are derived from minute irregularities in the barrel produced during the manufacturing process. The examination of these striations on the land marks and groove marks of the projectile is difficult using conventional optical microscopy. However, digital imaging techniques have the potential to detect the presence of striations on ballistics specimens for identification matching. This paper describes a linescan imaging technique to examine the striation markings on the land marks and groove marks of projectiles for positive identification. The paper discusses the application of the technique to cylindrical forensic ballistics specimens, and the potential of the technique for image matching. Digital images of land marks and groove marks of projectiles produced by the line scan technique are presented, and analyses of the images are conducted.