Fired bullets and ejected cartridge cases have unique ballistics signatures left by the firearm. By analyzing the ballistics signatures, forensic examiners can trace these bullets and cartridge cases to the firearm used in a crime scene. Current automated ballistics identification systems are primarily based on image comparisons using optical microscopy. The correlation accuracy depends on image quality, which is largely affected by lighting conditions. Because ballistics signatures are geometrical micro-topographies by nature, direct measurement and correlation of the surface topography is being investigated for ballistics identification. A Two-Dimensional (2D) and Three-Dimensional (3D) Topography Measurement and Correlation System was developed at NIST for certification of Standard Reference Material (SRM) 2460/2461 Bullets and Cartridge Cases. This system included contact and non-contact topography measurements instruments and a correlation software. A feasibility assessment for ballistics identifications of bullets and cartridge cases based on the topography measurement and correlation of ballistics signatures is currently being investigated at NIST. Equipment includes a stylus-profiling instrument with wide dynamic range and three-dimensional profiling function, an interferometric microscope, a Nipkow disk confocal microscope, and a stylus-laser surface profiler, which can perform both the contact and non-contact surface profiling. An Integrated Ballistics Identification System (IBIS) at a crime laboratory can also be made available.

 

Reference

Song J, et al: Measurement Science Review 10 (2): 19, 2010, DOI: 10.2478/v10048-010-0004-8

 

key words

Forensic science; Topography measurement; Surface metrology; Ballistics identification; Standard bullet; Standard cartridge case; Law enforcement standard;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants