A Comparison of Sensofar S Neox 3D Optical Profiler 2D and 3D Scans

Jocelyn Mayo*, Keith Morris, Ph.D.
Eberly College of Arts and Sciences, West Virginia University, Morgantown, WV 26505

Presentation Category: Social & Behavioral Sciences (Poster presentation)

Student’s Major: Forensic and Investigative Science

The performance of a Sensofar Confocal Microscope will be tested using a set of cartridge cases fired from 42 Luger firearms of the 9 mm caliber. This microscope has the ability to take both 2D grayscale and 3D topography scans. Cartridge case scans are utilized in the discipline of firearm examination in forensic science because they can use the varying depths on a cartridge case to identify individualizing characteristics to make known match comparisons. According to the PCAST Report of 2016, firearm examination should not be admissible in court, due to the subjectivity of identifying the specific location and depths of subclass characteristics to be the same. Current technological advances in microscopes has allowed an increase in the ability to prove less subjective conclusions. This will allow firearm examination to have less false positives, leading to fewer incorrect convictions, and greater admissibility in court. In this study, ROC curves will be generated for each firearm in order to demonstrate the ability of each type of scan to make match to known-match comparisons. Scans will be cropped using MatLab, cropping out the firing pin impression to amplify the breech face. ROC curves and AUC characteristics will be compared in order to determine the true positive rate of success. It is believed that 3D scans will have a higher rate of success due to their ability to examine the entire breech face. It was found in past studies that 3D scans did have a higher success rate, indicated by a larger AUC and ROC ratio comparison. The 3D scans were also found to have a true positive increase, indicating less subjectivity and fewer false positives compared to manual comparison and 2D scans.

Funding: Not funded

Program/mechanism supporting research/creative efforts: WVU's Research Apprenticeship Program (RAP) & accompanying HONR 297-level course