Evaluation of 3D Virtual Comparison Microscopy for Firearm Forensics within the Crime Lab

Over the past several years, advances in 3D surface metrology have made their way into the field of firearm and toolmark analysis. Accurate surface imaging coupled with highresolution visualization tools and advanced algorithms are beginning to allow examiners to view, annotate, and share data between labs, to conduct blind verification, and to form a statistical basis for identification. In 2016, the President's Council of Advisors on Science and Technology (PCAST) issued a report critical of toolmark analysis and called for additional research into the establishment of error rates. The aims of this proposal address a critical aspect of the recent PCAST report while advancing the field of 3D scanning and analysis for firearm forensics. First, we will investigate the effect of scan resolution on an examiner's ability to reach accurate conclusions. Second, we will deploy scanning systems to two crime labs and evaluate the use of virtual comparison microscopy within the lab. The proposed work includes critical steps towards further validating the field of toolmark examination and the use of 3D scanning technology in the forensic lab. Building from our recent success in the 3D scanning and analysis of cartridge cases, the proposed work takes important next steps towards moving the developed technology into the crime lab. The establishment of Virtual Comparison Microscopy will require knowledge of requirements and best practices. Our recent study demonstrated that VCM can be successful with high-resolution surface topographies, yet the effects of lower-resolution scans remains unknown. This is a critical question to answer as more and more labs consider the purchase of scanning systems from a variety of vendors each with different resolution specifications. In Aim 1 we will complete a VCM study to investigate the effect of scan resolution on examiner performance. We anticipate high accuracy with high-resolution scans and more calls of inconclusive as scan resolution decreases. The use of our validated VCM tools and its ability for user annotation will allow us to gain insights into which types of features require high-resolution scans. In Aim 2 we will complete two deployment studies to evaluate VCM and VCM workflows within the lab. The work directly addresses the CFDA 16.560 solicitation's Development goal of producing novel and useful systems and methods and the Fundamental/Basic Research Goals of improving the understanding of the accuracy, reliability, and measurement validity of forensic science disciplines. This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). CA/NCF