Norman D G, Baier W, Watson D G, Burnett B, Painter M, Williams M A
WMG, International Manufacturing Centre, University of Warwick Coventry, CV4 7AL, UK.
Department of Psychology, University of Warwick Coventry, CV4 7AL, UK.
Forensic Sci Int. 2018 Dec;293:91-100. doi: 10.1016/j.forsciint.2018.10.027. Epub 2018 Nov 3.
In toolmark analysis, microscopy techniques, such as micro-CT, are used to visualise and measure toolmarks left on bones by a tool. In dismemberment cases, properties such as the width of the saw mark can provide cues to which tool was used by the culprit. The aim of the current study was to establish whether; (i) micro-CT is an appropriate imaging technique for saw mark analysis, (ii) toolmarks statistically differ when created with different tools, (iii) toolmark width can predict tool blade width, and (iv) toolmarks differ if created under different methodological conditions. Across two experiments, 270 saw marks were created using eight tools with either a controlled or free saw action on either fleshed or defleshed human long bone. Toolmarks were micro-CT scanned and seven toolmark properties were categorised or measured by two independent raters. The current study found that; (i) micro-CT was found to be a powerful and reliable imaging method for the visualisation and measurement of saw mark properties, (ii) toolmark properties differed significantly within and between various methodological conditions (p<.001) when created by eight different tools, (iii) a regression model developed using toolmark widths from Experiment 2 overall predicted 94% of tool widths in Experiment 1, and iv) methodological factors such as tissue presence and saw action significantly and inconsistently influenced toolmark properties for different tools. The study further validates the use of mirco-CT for saw mark analysis and demonstrates the potential of using toolmark properties to determine the tool used in cases of dismemberment. Given the effects that methodological factors such as tissue presence can have on toolmark properties, future studies should use experimental set ups with fleshed human tissue and use a free saw action.
在工具痕迹分析中，诸如微型计算机断层扫描（micro-CT）等显微镜技术被用于可视化和测量工具在骨头上留下的工具痕迹。在肢解案件中，锯痕宽度等特征可以为识别犯罪者使用的工具提供线索。本研究的目的是确定：（i）微型计算机断层扫描是否是用于锯痕分析的合适成像技术；（ii）使用不同工具制造的工具痕迹在统计学上是否存在差异；（iii）工具痕迹宽度能否预测工具刀片宽度；以及（iv）在不同方法条件下制造的工具痕迹是否存在差异。在两个实验中，使用八种工具在带肉或去肉的人类长骨上以受控或自由锯切动作制造了270条锯痕。对工具痕迹进行了微型计算机断层扫描，并由两名独立评估人员对七种工具痕迹特征进行了分类或测量。本研究发现：（i）微型计算机断层扫描被发现是一种用于可视化和测量锯痕特征的强大且可靠的成像方法；（ii）当由八种不同工具制造时，在各种方法条件内和之间，工具痕迹特征存在显著差异（p<0.001）；（iii）使用实验2中的工具痕迹宽度建立的回归模型总体上预测了实验1中94%的工具宽度；以及（iv）诸如组织存在和锯切动作等方法因素对不同工具的工具痕迹特征有显著且不一致的影响。该研究进一步验证了微型计算机断层扫描在锯痕分析中的应用，并证明了利用工具痕迹特征来确定肢解案件中使用的工具的潜力。鉴于诸如组织存在等方法因素对工具痕迹特征可能产生的影响，未来的研究应使用带有带肉人体组织的实验设置，并采用自由锯切动作。
