Cammarota Valentina, Schnegg Michael, Massonnet Geneviève
University of Lausanne, School of Criminal Justice, Batochime, CH-1015 Lausanne - Dorigny, Switzerland.
University of Lausanne, School of Criminal Justice, Batochime, CH-1015 Lausanne - Dorigny, Switzerland.
Forensic Sci Int. 2019 Mar;296:132-143. doi: 10.1016/j.forsciint.2019.01.006. Epub 2019 Jan 17.
Edged weapons are frequently used to commit violent crimes (e.g., homicides, assaults or sequestrations). Following a stabbing, a fibre transfer might occur from the damaged fabric to the blade. It is crucial to investigate whether the target fibres were transferred to the blade as a result of the stabbing and if they are in association with the offence or whether they originate from another unrelated event (i.e., part of the background). The aim of this study is to explore the background population of fibres recovered on knife blades (police seizures and everyday knives) to help the interpretation of the results stemming from the analysis of the fibre evidence in crime cases involving the use of a bladed weapon. A population study was carried out to learn about the variety, the distribution and the size of the fibre population present on knife blades. After recovery using tapes lifting, stereoscopic examinations were performed to classify around 1500 fibres according to their colour and generic type. The most common colour/type combinations were: colourless/white cotton (31%), blue cotton (16%) and grey cotton fibres (11%). As blue fibres represent one of the most common colour group, they were selected to carry out a colour block study (based on microscopy observations and microspectrophotometry UV-vis spectra) to investigate the number and the size of the groups of indistinguishable fibres present on each blade. Only 30% of the knife blades presented more than one blue cotton fibre. The number of groups found per knife varied between 1 and 3, each group containing between 2 and 6 fibres. Findings revealed an important difference between the background fibre populations in terms of quantity of fibres, their morphology and spatial distributions - and the population of fibres transferred in a stabbing. The collected data can be used in a Bayesian approach to help with the interpretation of results.
利器经常被用于实施暴力犯罪（如杀人、袭击或绑架）。刺伤事件发生后，可能会有纤维从受损织物转移到刀刃上。至关重要的是要调查目标纤维是否因刺伤而转移到刀刃上，以及它们是否与犯罪有关，或者它们是否源自另一个不相关的事件（即背景的一部分）。本研究的目的是探索在刀刃上发现的纤维背景群体（警方缴获的刀具和日常刀具），以帮助解释涉及使用利刃武器的犯罪案件中纤维证据分析的结果。开展了一项群体研究，以了解刀刃上纤维群体的种类、分布和尺寸。使用胶带提取后，进行立体检查，根据颜色和通用类型对约1500根纤维进行分类。最常见的颜色/类型组合为：无色/白色棉纤维（31%）、蓝色棉纤维（16%）和灰色棉纤维（11%）。由于蓝色纤维是最常见的颜色组之一，因此选择它们进行色块研究（基于显微镜观察和紫外-可见微分光光度法光谱），以调查每把刀刃上无法区分的纤维组的数量和尺寸。只有30%的刀刃上出现了不止一根蓝色棉纤维。每把刀上发现的纤维组数量在1至3个之间，每个组包含2至6根纤维。研究结果揭示了背景纤维群体在纤维数量、形态和空间分布方面与刺伤中转移的纤维群体之间的重要差异。收集到的数据可用于贝叶斯方法，以帮助解释结果。
