Monday, April 03, 2017

Development of a Mobile, Automated Tool Mark Characterization/Comparison System

Authors: L.S. Chumbley, S. Zhang, M. Morris 

This project developed a portable prototype instrument that provides forensic examiners with the ability to characterize a tool-marked surface, compare the data from that surface to data files obtained from any other surface, and assess the likelihood that the two surfaces were made by using the same tool.

Acquisition of data is conducted using a system based on a portable 3-D optical profilometer manufactured by Alicona, GmbH. Comparison of resulting data files is done objectively using software algorithms developed and tested by researchers at Ames Laboratory/Iowa State University.
Small size permits portability to crime scenes when necessary. The software package used for analysis is called "Mantis." It is designed to be user friendly and uses open-source software code to allow for continued research and expansion. Currently, an examiner can use the system to compare all types of tool-marked surfaces, obtain objective statistical evaluation of data files, and clarify factors that existed when certain types of tool marks were made.

To date, the system has been successfully tested on data sets consisting of fully striated marks created from 50 sequentially manufactured screwdrivers, quasi- striated markings produced by 50 sequentially manufactured shear-cut pliers, and impression marks produced by 50 sequentially manufactured cold chisels.

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