NCJ Number
223877
Journal
Journal of Forensic Sciences Volume: 53 Issue: 4 Dated: July 2008 Pages: 876-883
Date Published
July 2008
Length
8 pages
Annotation
In a case study that involved an improvised pipe bomb with a drilled fuse hole, researchers determined whether or not a drill bit was used to make the hole and, if so, whether a drill bit produces well-defined tool marks that can be matched to a particular bit.
Abstract
The study determined that drill bit use or nonuse can be determined by examining three indicators: the presence of trace deposits in the form of particles and/or smears on the drill bit, especially inside the flute and the tip area; physical damage to the bit, including chipping, abrasion, and fissuring on the bit; and thermal damage. One or any combination of all three indicators could be used for determining the use of a drill bit. The study also concluded that no mechanical break-in period is needed in order to obtain reproducible tool marks from newly manufactured or unused drill bits. Toolmarks made on the drilled hole were well defined and could be individually associated either with recovered or test drilled holes. A recent case that contained evidence collected from five post blast bomb scenes and two residences of three suspects was submitted to the laboratory for examination. During one of the residence searches, a ¼-inch diameter drill bit was recovered. An intact steel pipe device filled with Hodgdon Pyrodex powder was recovered from another suspect’s residence. Two fragmented galvanized iron end caps recovered from two postblast scenes also had ¼-inch diameter drilled holes in their faceplates. The drill bit found in the residence appeared to be unused, with no visual wear or damage. This paper describes the materials and methods used in the testing that produced the aforementioned findings and conclusions. 9 figures and 19 references