Development of a Mobile, Automated Tool Mark Characterization/Comparison System

The PIs propose the development of a prototype instrument designed to provide forensic examiners with the ability to characterize a tool marked surface, compare the data from that surface to data files obtained from any other surface, and evaluate the likelihood that the two surfaces were made using the same tool. While the areas selected for characterization are at the discretion of the examiner, acquisition of the data will be carried out automatically. Comparison of resulting data files will be made in an objective manner using software algorithms developed and tested by researchers at Ames Laboratory / Iowa State University (AL/ISU). The instrument to be developed will be based on a portable 3-D optical profilometer manufactured by Alicona, Inc. and development will be undertaken with their assistance and cooperation. Since much of the actual hardware needed already exists physical assembly of a prototype instrument should be achieved relatively easily. Due to the relatively small size of the instrument, it is anticipated that the actual device will be portable, allowing it to be taken directly to crime scenes if need be. A large part of the effort will involve integration of software developed by AL/ISU into the operating parameters of the profilometer. A software package called “Mantis,” for Mark and Tool Inspection Suite, is under development that incorporates all of the algorithms developed at AL/ISU for striated toolmark analysis. This includes the routine “Matchmaker,” which allows for objective comparison of toolmarked surfaces and provides a statistical measure of the probability of the match by using an internal calibration routine, and “Markmaker”, a software routine that allows generation of a virtual tool tip that can be manipulated and used to estimate the exact force, angle of attack, and twist-angle that existed when the evidence mark was made. While the software suite is still in the preliminary stages, it promises to be extremely user friendly and easy to operate. The software will also be expandable, to include future algorithms designed to evaluate more complex multivariate marks such as impression evidence and shear marks. We plan to test the viability of the prototype by placing it into the hands of actual forensic examiners for them to use and conduct a series of tests.

The proposed instrument would serve as a prototype system that could enhance current efforts as exemplified by the National Integrated Ballistics Network (NIBIN). As such it should be recognized that it will still be a research system, not one suitable for immediate and widespread use. However, if successful the system would: 1) be able to compare all types of tool marked surfaces; 2) be portable; 3) provide objective statistical evaluation of data files; 4) elucidate factors that existed when the tool mark was made; 5) provide an open source platform that other researchers can write algorithms for and test, while offering data-files that can be used by any system or researcher; and hopefully 6) provide all these benefits at a greatly reduced hardware cost as compared to current systems in use.