This article summarizes the outcomes and methodology of a NIJ-funded project that developed a prototype system reported to enable "low-cost, portable, objective analysis of tool marks."
The researchers view the prototype as a "first-step" in providing forensic examiners at a crime scene with the ability to characterize a tool-marked surface, compare the data from that surface to data files obtained from other surfaces, and assess the likelihood that the two surfaces match, using a statistical algorithm. The prototype enables non-contact acquisition of data from both flat and curved surfaces; and it also provides data from steep-sided samples, such as the end of a screwdriver. The prototype consists of an optical profilometer for measuring surface roughness, a traveling case, and a laptop computer that runs modified software simplified to facilitate training. The system weighs approximately 80 pounds and fits in a suitcase. Once the prototype was assembled, the researchers first used it to measure a set of 50 sequentially manufactured screwdriver tips. As the software evolved, additional samples were analyzed, including 50 sequentially manufactured shear-cut pliers and 50 cold chisels. More complex analyses of bullets and knife cuts were also done, but with less success due to the large size of the data files created. The researchers recommend further development of statistical algorithms, improvements to the software, and an upgrade of the entire system so as to better capture images of cylindrical objects.