Statistical Validation of the Individuality and Repeatability of Striated Tool Marks: Screwdrivers and Tongue and Groove Pliers

• NCJ Number: 230715
• Journal: Journal of Forensic Sciences Volume: 55 Issue: 2 Dated: March 2010 Pages: 348-357
• Author(s): Benjamin Bachrach, Ph.D.; Anurag Jain, M.S.; Sung Jung, M.S.; Robert D. Koons, Ph.D.
• Date Published: March 2010
• Length: 10 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America
• Note: Presented in part at the Association of Firearms and Tool Marks Examiners (AFTE) conferences in 2005 and 2006.

Annotation

Tool mark identification relies on the premise that microscopic imperfections on a tool's working surface are sufficiently unique and faithfully transferred to enable a one-to-one association between a tool and the tool marks it creates. This paper presents a study undertaken to assess the validity of this premise.

Abstract

As part of this study sets of striated tool marks were created under different conditions and on different media. The topography of these tool marks was acquired and the degree of similarity between them was quantified using well-defined metrics. An analysis of the resulting matching and nonmatching similarity distributions shows nearly error-free identification under most conditions. These results provide substantial support for the validity of the premise of tool mark identification. Because the approach taken in this study relies on a quantifiable similarity metric, the results have greater repeatability and objectivity than those obtained using less precise measures of similarity. Figures, tables, and references (Published Abstract)