NCJ Number
246003
Journal
Journal of Forensic Sciences Volume: 59 Issue: 4 Dated: July 2014 Pages: 950-959
Date Published
July 2014
Length
10 pages
Annotation
This study introduces a tool mark analysis approach based upon 3D scans of screwdriver tip and marked plate surfaces at the micrometer scale from an optical microscope.
Abstract
This study introduces a tool mark analysis approach based upon 3D scans of screwdriver tip and marked plate surfaces at the micrometer scale from an optical microscope. An open-source 3D graphics software package is utilized to simulate the marking process as the projection of the tip's geometry in the direction of tool travel. The edge of this projection becomes a virtual tool mark that is compared to cross-sections of the marked plate geometry using the statistical likelihood algorithm introduced by Chumbley et al. In a study with both sides of six screwdriver tips and 34 corresponding marks, the method distinguished known matches from known nonmatches with zero false-positive matches and two false-negative matches. For matches, it could predict the correct marking angle within +/- 5-10 degrees . Individual comparisons could be made in seconds on a desktop computer, suggesting that the method could save time for examiners. Abstract published by arrangement with Wiley.