2013
Robert Thompson
Albuquerque, NM
The NIST Ballistics Identification System (NBIS) is developed based on 3D topography measurements on correlation cells, and aims to provide objective, high-accuracy, and high-speed ballistics identifications. The National Ballistics Evidence Search Engine (NBESE) is proposed by NIST for ballistics evidence searches using the Congruent Matching Cells (CMC) method with system interoperability and error rate reporting. Since most existing ballistic identification systems are based on intensity image comparisons, it is necessary to conduct a validation test that demonstrates the feasibility of the CMC method for the identifications of optical intensity images. A Leica comparison microscope is used to capture the breech face intensity images of the same set of 40 cartridge cases fired from handguns with 10 consecutively manufactured pistol slides. In the correlation tests using the CMC method, a total of 780 correlations including 63 KM and 717 KNM were implemented. In the initial tests using the single correlation parameter of the whole image the KM and KNM distributions cannot be separated. However, by using the CMC method with three identification parameters the KM and KNM distributions show clear separations without any overlap. The results show that the CMC method works well for correlation of both the 3D topographies and optical intensity images.