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Statistical Confirmation of Empirical Observations Concerning Tool Mark Striae

NCJ Number
AFTE Journal Volume: 39 Dated: 2007
Date Published

In performing the statistical confirmation of empirical observations of tool mark striae, this project focused on toolmarks produced by 44 sequentially manufactured screwdriver tips characterized for surface roughness using a profilometer.


Toolmarks were produced in lead at angles of 30°, 60°, and 85°. A computer program developed to compare and match the profilometer data has been used to show that marks from a single tip produced at similar angles yield much higher correlation values than marks produced from the same tip but at different angles. This analysis provides statistical support for the widely-accepted empirical observation that toolmark striae must be reproduced at similar angles in order to be unambiguously identified as being made by a particular tool. (Publisher Abstract)

Date Published: January 1, 2007