AFTE Store - Performance Comparison of an IBIS® Heritage™ System with an IBIS® TRAX-HD3D™ System

A West Virginia University (WVU) IBIS® Heritage™ System and the new IBIS® TRAX-HD3D™ System were used, with
the cooperation of Ultra Electronics Forensic Technology, Inc. (FTI), to compare the results of a 3D IBIS® analysis to
those of a 2D IBIS® analysis (both the 2D and 3D capabilities of the Trax™ were utilized). The test-fired cartridge cases from a sample set of twelve 9 mm Luger firearms were used to study 2D and 3D correlations; the intra- and inter-variation of the results from both systems were also analyzed. These twelve firearms were selected as a representation of the firearms in the WVU collection. The receiver operating characteristic (ROC) curve demonstrates the discriminating power of the method by determining how well it can differentiate between known match and known non-match cartridge cases. The least discriminating feature when using the Heritage™ System (only 2D) was the breech face while the highest discriminating feature was the firing pin. The least discriminating feature of the Trax™ System was the breech face (2D) whereas the best discriminating feature was the firing pin (2D). Although a firearm examiner may generally find the breech face to contain more information for comparison, the IBIS attributed higher scores to the firing pin impressions. Over 60% of the firearms displayed a significant increase in the area under the curve (AUC) values for the Trax™ 3D breech face scores over the Heritage™ breech face scores, indicating better performance in that aspect with this set of firearms. Furthermore, use of the side-light feature for analyzing breech face marks using the Trax™ System resulted in better discrimination versus the nonside-lit breech face scores; 75% of the cartridge cases showed a significant increase in the AUC values with the side-light feature of the Trax™ System compared with the Heritage™ System. The Trax™ System did not show the same increase in performance with 3D firing pin scores, as the Heritage™ System had a higher average AUC based on firing pin scores.