Analyzing Cut Mark Characteristics on Bone from Chopping/Hacking Tools

Abstract

Sharp force trauma (SFT) is a mechanism of traumatic injury in which a tool with a slanted edge impacts the skin and/orbone, producing a cut mark. While experimental SFT research has been conducted utilizing smaller tools, minimal research focuses on damage inflicted by chopping/hacking tools. Thus, the purpose of this research was to experimentally evaluate and analyze macroscopic characteristics of chopping/hacking trauma inflicted on pig bones (Sus scrofa domesticus) to determine if differentiation of tool class type can be made. An additional goal of this study was to develop a standardized approach to chopping/hacking research to provide appropriate comparisons between the results of different macroscopic experimental studies. Trauma was inflicted to 20 partially fleshed pig limbs utilizing four chopping/hacking tools (axe, hatchet, machete, and cleaver) as well as a carving knife for comparison. Macroscopic evaluation of 16 cut mark characteristics commonly described in the forensic literature was conducted to assess statistical significance. Utilizing a chi-squared analysis, three of the 16 cut mark characteristics (wall regularity, kerf bisection, and edge chattering) demonstrated statistically significant differences in relation to the tool utilized, although Cramer’s V correlations indicated weak to moderate effect sizes. A Fleiss kappa analysis indicated substantial agreement during a test for interobserver error regarding characteristics for each tool type and characteristics regardless of tool type. Similar trends in wall regularity, kerf bisection, and edge chattering have been demonstrated in the current experimental literature. Overall, this study confirmed that the ability to differentiate chopping/hacking tools from macroscopic characteristics is challenging.