NCJ Number
212649
Journal
Journal of Forensic Sciences Volume: 50 Issue: 6 Dated: November 2005 Pages: 1407-1410
Date Published
November 2005
Length
4 pages
Annotation
Because it is always preferable to examine and compare the actual negative questioned toolmarks from the crime scene with negative test toolmarks made with the suspected tool, this study tested alternative materials for producing known standard test impressions.
Abstract
Traditionally, toolmark test exemplars are produced by applying a tool's working surface to a piece of soft metal such as lead. Soft, pliable metals are primarily used for this purpose because they will replicate the microscopic grooves present on a tool's working surface without damaging the tool. Other materials, such as single and double component silicone casting materials have been used with some success at crime scenes in order to preserve and record questioned toolmarks present on objects that are not practical to remove from the crime scene. Although these substances are useful as forensic casting material, they produce positive impressions of questioned tool marks, which are not as useful as negative impressions. The authors used an alternative material for the preparation of test toolmarks, i.e., jewelry modeling or carving waxes. These waxes are designed for use in the jewelry modeling industry in creating very fine, highly detailed wax models of jewelry pieces that will be cast in various metals that use the lost wax casting method. Jeweler's waxes have been found to be ideal for preparing test toolmarks from exemplar tools. The test tool's working surface is applied to a piece of the appropriate wax in a manner consistent with the tool's design. The replicas obtained are exact, highly detailed, 1:1, negative impressions of the exemplar tool's working surface, have a long shelf-life, and are suitable for use in toolmark examination and comparison cases. They reveal in fine detail the class characteristics, wear patterns, damage, and accidental markings present on the tool's surface. 1 table, 4 figures, and 8 references