Reciprocating saws as tools of dismemberment: analysis of class characteristics and practical utility
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The present research examined the features that may differentiate cuts made in bone by mechanical and hand-powered saws, specifically investigating the characteristics of commercially available reciprocating saws. The partial limbs of adult white-tailed deer (Odocoileus virginianus) were used as a proxy for human remains, and were cut using five commercially available reciprocating saw blades and a hand-powered hacksaw. The reciprocating blades tested ranged from five teeth-per-inch to 14/18 teeth-per-inch and included raker, alternating, and wavy tooth sets. The hacksaw blade had 32 teeth-per-inch, with wavy set teeth. All the blades examined were intended to cut wood, metal, or both materials. The resulting false start kerfs and complete kerfs on the remains were then examined macroscopically and microscopically. The present study utilized both qualitative and quantitative analysis to examine kerf features that characterize reciprocating saws. The presentation of specific features within the kerf varied based upon blade properties, how the implement was powered, and how it was wielded in reference to the material. The results of the present study demonstrated that significant differences do exist between reciprocating saw blades. Kerf characteristics in which significant differences were noted include: kerf false start (cross section) shape, frequency of cut surface drift, presence of harmonics, striation regularity, and exit chipping size. Inter-blade differences generally reflect class characteristics previously established for hand-powered blades, though reciprocating blades do not strictly follow these categorizations (Symes 1992; Symes et al. 1998, 2010). Identification of inter-blade differences allows the limited identification of sub-classes within reciprocating saws based on the above characteristics, though blades cannot be uniquely identified. Additionally, interior exit chipping was noted, which has not been mentioned in previous sharp force trauma research. Ultimately, this research has applications for sharp force trauma analysis and further aids in the identification of reciprocating saw use in a forensic context, including dismemberments.