Steensma Kristy, Ansell Ricky, Clarisse Lindy, Connolly Edward, Kloosterman Ate D, McKenna Louise G, van Oorschot Roland A H, Szkuta Bianca, Kokshoorn Bas
Division Biological Traces, Netherlands Forensic Institute, P.O. Box 24044, 2490 AA, The Hague, The Netherlands.
Swedish National Forensic Centre, SE-581 94, Linköping, Sweden; Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83, Linköping, Sweden.
Forensic Sci Int Genet. 2017 Nov;31:95-104. doi: 10.1016/j.fsigen.2017.08.015. Epub 2017 Aug 19.
To address questions on the activity that led to the deposition of biological traces in a particular case, general information on the probabilities of transfer, persistence and recovery of cellular material in relevant scenarios is necessary. These figures may be derived from experimental data described in forensic literature when conditions relevant to the case were included. The experimental methodology regarding sampling, DNA extraction, DNA typing and profile interpretation that were used to generate these published data may differ from those applied in the case and thus the applicability of the literature data may be questioned. To assess the level of variability that different laboratories obtain when similar exhibits are analysed, we performed an inter-laboratory study between four partner laboratories. Five sets of 20 cable ties bound by different volunteers were distributed to the participating laboratories and sampled and processed according to the in-house protocols. Differences were found for the amount of retrieved DNA, as well as for the reportability and composition of the DNA profiles. These differences also resulted in different probabilities of transfer, persistence and recovery for each laboratory. Nevertheless, when applied to a case example, these differences resulted in similar assignments of weight of evidence given activity-level propositions.
为解决特定案件中导致生物痕迹沉积的活动相关问题，有必要了解相关场景下细胞物质转移、留存和恢复概率的一般信息。当包含与案件相关的条件时，这些数据可从法医文献中描述的实验数据得出。用于生成这些已发表数据的采样、DNA提取、DNA分型和图谱解读的实验方法可能与案件中应用的方法不同，因此文献数据的适用性可能受到质疑。为评估不同实验室在分析类似物证时获得的变异性水平，我们在四个合作实验室之间开展了一项实验室间研究。将五组由不同志愿者捆绑的20个束线带分发给参与实验室，并按照内部规程进行采样和处理。在回收DNA的量以及DNA图谱的可报告性和组成方面发现了差异。这些差异也导致每个实验室的转移、留存和恢复概率不同。然而，当应用于一个案例时，这些差异在基于活动水平假设给出的证据权重分配上结果相似。
