Campus Units

Materials Science and Engineering, Ames Laboratory

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

3-2015

Journal or Book Title

Journal of Forensic Sciences

Volume

60

Issue

2

First Page

303

Last Page

314

DOI

10.1111/1556-4029.12642

Abstract

Due to historical legal challenges, there is a driving force for the development of objective methods of forensic toolmark identification. This study utilizes an algorithm to separate matching and nonmatching shear cut toolmarks created using fifty sequentially manufactured pliers. Unlike previously analyzed striated screwdriver marks, shear cut marks contain discontinuous groups of striations, posing a more difficult test of algorithm applicability. The algorithm compares correlation between optical 3D toolmark topography data, producing a Wilcoxon rank sum test statistic. Relative magnitude of this metric separates the matching and nonmatching toolmarks. Results show a high degree of statistical separation between matching and nonmatching distributions. Further separation is achieved with optimized input parameters and implementation of a “leash” preventing a previous source of outliers—however complete statistical separation was not achieved. This paper represents further development of objective methods of toolmark identification and further validation of the assumption that toolmarks are identifiably unique.

Comments

This is the peer-reviewed version of the following article: Spotts, Ryan, L. Scott Chumbley, Laura Ekstrand, Song Zhang, and James Kreiser. "Optimization of a statistical algorithm for objective comparison of toolmarks." Journal of Forensic Sciences 60, no. 2 (2015): 303-314, which has been published in final form at DOI: 10.1111/1556-4029.12642 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Posted with permission.

Copyright Owner

American Academy of Forensic Sciences

Language

en

File Format

application/pdf

Published Version

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