Proposed “NIST Ballistics Identification System (NBIS)” Based on 3D Topography Measurements on Correlation Cells*

The National Institute of Standards and Technology (NIST) has proposed a “NIST Ballistics Identification System (NBIS)” to facilitate accurate ballistics identifications and fast evidence searches [1]. The NBIS will use three-dimensional (3D) topography measurements for ballistics identification and evidence searches. The 3D topographies will be subdivided into arrays of correlation cells in order to help identify “valid correlation areas” and eliminate “invalid correlation areas” from the matching and identification procedure. “Synchronous processing” is proposed for correlating dozens or even hundreds of cell pairs at the same time. Based on the concept of correlation cells, a “Contiguous Matching Cells (CMC)” method using three identification parameters of the paired correlation cells (cross correlation function maximum CCFmax, spatial registration position in x-y and registration angle θ) is proposed for high accuracy ballistics identifications. Based on the proposed CMC method, a “National Ballistics Evidence Search Engine (NBESE)” is also proposed for fast and accurate ballistics evidence searches. The proposed NBIS and NBESE can be used for correlations of both geometrical topographies and optical intensity images, and can be potentially applied for all case scenarios of fired bullets, cartridge cases and toolmarks. All the parameters and algorithms will be in the public domain and subject to open tests. An error rate reporting procedure will be developed that can greatly add to the scientific support for the firearm and toolmark identification specialty, and give confidence to the trier of fact in court proceedings. Both the NBIS and NBESE will be engineered to employ publicly available software and database file protocols, and provide published search algorithms and statistical models. In this way interoperability between different ballistics identification systems using this invention can be more easily achieved. This interoperability will make the NBIS and NBESE suitable for ballistics identifications and evidence searches with large national databases, such as those of the National Integrated Ballistic Information Network (NIBIN) in the United States, as well as national databases in the European Network of Forensic Science Institutes (ENFSI). link questioned bullets and cartridge cases to the firearm used in a crime. Current automated ballistics identification systems are primarily based on image comparisons using optical microscopy. The correlation accuracy of these systems depends on image quality, which is largely affected by lighting conditions [3]. Because ballistics signatures are geometrical micro-topographies by nature, systems for direct measurement and correlation of surface topography have been researched and developed for ballistics identification [4-6]. NIST has developed Standard Reference Material (SRM) bullets and cartridge cases [7] which are being used in crime laboratories as reference standards in the United States and internationally. NIST has also developed a 2D/3D ballistics signature acquisition and correlation system [7] for the certification measurements of the SRM bullets and cartridge cases to ensure the similarity of their ballistics Date Received: August 6, 2012 Peer Review Completed: February 21, 2013