Institute of Legal Medicine, Faculty of Medicine, University of Cologne, Melatengürtel 60-62, 50823, Cologne, Germany.
Institute for Forensic Sciences, Landeskriminalamt Nordrhein-Westfalen (LKA NRW), 40219, Düsseldorf, Germany.
Int J Legal Med. 2021 Sep;135(5):2117-2134. doi: 10.1007/s00414-021-02609-9. Epub 2021 May 13.
This work deals with the examination of tool marks in human cartilage. We compared the effectiveness of several cleaning methods on cut marks in porcine cartilage. The method cleaning by multiple casts achieved the significantly highest scores (P = 0.02). Furthermore, we examined the grain-like elevations (dots) located on casts of cut cartilage. The results of this study suggest that the casting material forms these dots when penetrating cartilage cavities, which are areas where the strong collagen fibres leave space for the chondrocytes. We performed fixation experiments to avoid this, without success. In addition, 31 casting materials were compared regarding contrast under light-microscope and 3D tool marks scanner. Under the light-microscope, brown materials achieved significantly higher values than grey (P = 0.02) or black (P = 0.00) whereas under the 3D scanner, black materials reached higher contrast values than grey (P = 0.04) or brown (P = 0.047). To compare the accuracy and reproducibility of 6 test materials for cartilage, we used 10 knives to create cut marks that were subsequently scanned. During the alignment of the individual signals of each mark, the cross-correlation coefficients (X) and lags (L) were calculated. The signals of the marks in agarose were aligned with significantly fewer lags and achieved significantly higher cross-correlation coefficients compared to all tested materials (both P = 0.00). Moreover, we determined the cross-correlation coefficients (X) for known-matches (KM) per material. Agarose achieved significantly higher values than AccuTrans®, Clear Ballistics™, and gelatine (all P = 0.00). The results of this work provide valuable insights for the forensic investigation of marks in human costal cartilage.
本工作研究了人类软骨上工具痕迹的检验。我们比较了几种清洁方法对猪软骨切割痕迹的效果。多次浇铸清洁法获得的评分显著最高（P=0.02）。此外，我们还研究了位于切割软骨铸型上的粒状隆起（点）。本研究结果表明，铸造材料在穿透软骨腔时会形成这些点，而软骨腔是胶原纤维强烈的地方，为软骨细胞留出了空间。我们为避免这种情况进行了固定实验，但没有成功。此外，我们比较了 31 种铸造材料在光镜下和 3D 工具痕迹扫描仪下的对比度。在光镜下，棕色材料的对比度显著高于灰色（P=0.02）或黑色（P=0.00），而在 3D 扫描仪下，黑色材料的对比度高于灰色（P=0.04）或棕色（P=0.047）。为了比较 6 种软骨测试材料的准确性和可重复性，我们使用 10 把刀制作了切割痕迹，然后对其进行扫描。在对每个痕迹的单独信号进行对齐时，计算了互相关系数（X）和滞后（L）。与所有测试材料相比，琼脂糖中的痕迹信号的滞后明显减少，互相关系数显著更高（均 P=0.00）。此外，我们确定了每种材料的已知匹配（KM）的互相关系数（X）。琼脂糖的 KM 值显著高于 AccuTrans®、Clear Ballistics™和明胶（均 P=0.00）。本工作的结果为法医调查人类肋软骨上的痕迹提供了有价值的见解。
