The Influence of Soft Tissue Presence and Sawing Methodology on Saw Mark Analyses

Abstract

Previous research in saw mark analysis has relied on non-human bone and/or has been conducted on defleshed bones stabilized with a vice during cutting, conditions that do not accurately replicate most forensic dismemberment scenarios. At present, no studies have empirically assessed how soft tissue and sawing methodology affect the presence and expression of saw cut features on complete cuts made in human samples. The present study aims to fill this gap by examining 638 complete cuts produced by an array of saws (n = 15) on fleshed human remains using free-sawing cutting versus defleshed human bones stabilized in a vice. Twelve categorical kerf features and four saw class characteristics (power, tooth shape, tooth set, teeth per inch) were assessed. Fisher’s and Fisher-Freeman-Halton exact tests indicate the following significant results: fleshed/free-sawing samples are more likely to present with entrance shaving, initial shaving, and polishing and less likely to present with breakaway spurs/notches, pull-out striae, tooth hop, and striation uniformity. Logistic regression analyses revealed important interactions between tissue/sawing methodology, saw class characteristics, and the presentation of kerf features, suggesting that saw characteristics do not equally impact these observed sample differences. These results indicate that tissue and sawing methodology may have more of an effect on kerf feature expression for some saws than others, underscoring the complexity of saw mark analysis research. Caution should be used when applying methods and statistics derived from defleshed, viced saw mark research to forensic dismemberment cases, given that tissue and sawing methodology may affect results, at least for some traits.