Firearms Toolmark Examination: A Scientific Evaluation

This introduction summarizes the results of a very detailed study performed by the author over his experience as an expert witness. All of the examples provided in that study utilize real firearms toolmark data from actual criminal cases. Some of the data from those cases appear in this introduction. A set of criteria are presented for evaluating the scientific validity of a procedure that consists of tools and techniques. Three approaches are described for performing firearms toolmark examinations -- the current technique using comparison microscopes, application of the AFTE Theory of Identification to the current technique of using comparison microscopes, and using laser scanning microscopes, surface profile parameters, and statistical hypothesis tests. Each of these approaches are evaluated for scientific validity using the identified criteria