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)