Scott K R, Morgan R M, Cameron N G, Jones V J
School of Natural Sciences & Psychology, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, United Kingdom; Department of Security & Crime Science, University College London, 35 Tavistock Square, London WC1H 9EZ, United Kingdom; Centre for the Forensic Sciences, University College London, 35 Tavistock Square, London WC1H 9EZ, United Kingdom.
Department of Security & Crime Science, University College London, 35 Tavistock Square, London WC1H 9EZ, United Kingdom; Centre for the Forensic Sciences, University College London, 35 Tavistock Square, London WC1H 9EZ, United Kingdom.
Sci Justice. 2019 May;59(3):292-305. doi: 10.1016/j.scijus.2018.11.004. Epub 2018 Nov 19.
Environmental indicators are increasingly sought and analysed in a range of forensic reconstructions. Although the majority of casework and research studies are concerned with the criminal investigation of terrestrial habitats (soils, sediments, plants etc.), freshwater environments are also frequently encountered as crime scenes. As such, microalgae, particularly diatoms, may provide useful circumstantial trace evidence following their transfer to a victim or perpetrator. Diatom analysis is a relatively underused technique in forensic ecology, although an increased empirical research focus is beginning to recognise the evidential value of a transferred assemblage. This study aimed to examine three of the spatial and temporal variables known to influence the extent of an initial transfer of trace particulates, within the context of freshwater diatoms to clothing. A series of experiments were designed to consider the impact of recipient surface characteristics (clothing type), source environment conditions (seasonality), and morphological (type of diatom) variability, on the total number (no. per cm) and species richness (total no. sp.) of an evidential diatom sample recovered from clothing. Nine commonly used clothing materials were immersed in a freshwater river at three times of year - the early and late spring and in the winter. Diatoms were recovered using a HO extraction technique and examined microscopically. The results demonstrated that diatom transfer to clothing varies significantly, with a greater abundance and a higher species richness transferred to coarse woven surfaces including acrylic, linen, and viscose. Significantly fewer diatoms were transferred to clothing in the winter, in line with seasonal fluctuations in the source environment diatom community. Furthermore, variation in the relative abundance of particular diatom species was identified between clothing types, provisionally suggesting that morphological characteristics may also support or limit the transfer of material. These findings highlight that, although clothing may offer a valuable repository of freshwater diatom trace evidence, the interpretation of evidential material should be approached within an exclusionary framework. Thus, empirical data has been generated to develop evidence bases within forensic ecology, demonstrating some of the spatial and temporal factors which may contribute to or limit the transfer of evidence.
在一系列法医重建工作中，人们越来越多地寻找和分析环境指标。尽管大多数实际案件工作和研究都涉及对陆地栖息地（土壤、沉积物、植物等）的刑事调查，但淡水环境也经常作为犯罪现场出现。因此，微藻，尤其是硅藻，在转移到受害者或犯罪者身上后，可能会提供有用的间接微量证据。硅藻分析在法医生态学中是一种相对未被充分利用的技术，不过，越来越多的实证研究开始认识到转移群落的证据价值。本研究旨在考察已知会影响微量颗粒物初始转移程度的三个时空变量，具体是在淡水硅藻转移到衣物的背景下进行考察。设计了一系列实验，以考虑受体表面特征（衣物类型）、源环境条件（季节性）和形态学（硅藻类型）变异性对从衣物上回收的证据性硅藻样本的总数（每平方厘米数量）和物种丰富度（物种总数）的影响。九种常用的衣物材料在一年中的三个时间点——早春、晚春和冬季——被浸入一条淡水河中。使用HO提取技术回收硅藻并进行显微镜检查。结果表明，硅藻向衣物的转移差异显著，转移到包括腈纶、亚麻和粘胶纤维在内的粗织表面的硅藻数量更多、物种丰富度更高。冬季转移到衣物上的硅藻明显更少，这与源环境硅藻群落的季节性波动一致。此外，还发现特定硅藻物种的相对丰度在不同衣物类型之间存在差异，初步表明形态特征也可能支持或限制物质的转移。这些发现突出表明，尽管衣物可能是淡水硅藻微量证据的宝贵储存库，但对证据材料的解释应在排除框架内进行。因此，已经生成了实证数据，以建立法医生态学的证据库，展示了一些可能有助于或限制证据转移的时空因素。
