title: Development of an objective method for the comparison of fired projectiles using an air pistol as a template.
abstract: The ability to objectify ballistic evidence is a challenge faced by firearms examiners around the world. A number of researchers are trying to improve bullet-identification systems to address deficiencies detailed within the National Academy of Science report (2009). More recently focus has turned to making use of more sophisticated imaging modalities to view entire regions of the projectile and the development of automated systems for the comparison of the topographical surfaces recorded. Projectiles from a newly bought air pistol with 0.177 calibre pellets (unjacketed), fired series of 609 pellets were examined using an optical microscope. A mathematical methodology was developed to pre-process the resultant topographical maps generating point data for comparison, analysed using the principal component analysis (PCA). In most cases limited to reasonable success was achieved. The objective method still requires an operator to identify the Land Engraved Areas to be scanned, however the mathematical alignments were objectively achieved. The PCA results illustrated that the striation marks were neither exclusive nor specific to the LEA regions but rather crossed over regions. This study also proves that a single weapon does not necessarily leave identical marks of projectiles on its surface.
authors.affiliation: Forensic Science Program, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia; Centre for Forensic Science, Department of Pure and Applied Chemistry, The University of Strathclyde, Royal College Building, 204 George Street, G1 1XW Glasgow, United Kingdom. Electronic address: raviera@yahoo.com.
authors.forename: Noor Hazfalinda
authors.initials: NH
authors.lastname: Hamzah
keywords: Acquired characteristics; Air weapon and pellets; Bullet-identification system; Principal component analysis; Surface topography measurements; Unjacketed bullets