College of Science & Engineering, Flinders University, Adelaide 5042, South Australia.
College of Science & Engineering, Flinders University, Adelaide 5042, South Australia.
Forensic Sci Int. 2023 Jul;348:111728. doi: 10.1016/j.forsciint.2023.111728. Epub 2023 May 9.
The persistence of touch DNA deposited after realistic handling of items typically encountered in forensic investigations has been the subject of few studies. Understanding the long-term persistence of touch DNA on different substrates in varying conditions can be central to the effective triage of samples for further processing. As the time between an alleged incident and collection of evidence may vary from a few days to years after an alleged event, this study assessed three different common substrates for the persistence of touch DNA over a time span up to 9 months. These substrates included fabric, steel, and rubber, each of which were handled in a way to imitate what may happen during a criminal act. The three substrates were exposed to two different environments for up to 9 months: inside a dark cupboard with no traffic to act as a control and an outside semi-exposed environment. Ten replicates from each of the 3 substrates were tested at 5 time points to create 300 samples. All samples were processed using a standard operating workflow to provide genotype data after exposure to different environments. It was found that the fabric samples produced informative STR profiles (defined here as 12 or more alleles) up to the 9 month timepoint for either environment. The rubber and steel substrates for the inside condition produced informative STR profiles up to the 9 month timepoint, but only generated informative STR profiles for the outside condition up to 3 and 6 months, respectively. These data add to our understanding of the external factors that affect DNA persistence.
真实处理法医学调查中常见物品后遗留的触摸 DNA 的持久性一直是少数研究的主题。了解不同底物在不同条件下触摸 DNA 的长期持久性对于有效筛选进一步处理的样本至关重要。由于涉嫌事件和证据收集之间的时间可能从涉嫌事件发生后的几天到几年不等，因此本研究评估了三种不同的常见底物在长达 9 个月的时间内触摸 DNA 的持久性。这些底物包括织物、钢和橡胶，每种底物的处理方式都模仿了犯罪行为中可能发生的情况。这三种底物在两种不同的环境中暴露长达 9 个月：一个没有交通的黑暗柜子作为对照，以及一个半暴露的外部环境。从每个 3 个底物中各取 10 个重复，在 5 个时间点进行测试，共创建 300 个样本。所有样本均采用标准操作流程进行处理，在暴露于不同环境后提供基因型数据。结果发现，织物样本在任何环境下，最长可在 9 个月的时间点产生有信息量的 STR 图谱（此处定义为 12 个或更多等位基因）。内部条件下的橡胶和钢底物最长可在 9 个月的时间点产生有信息量的 STR 图谱，但仅在 3 个月和 6 个月时分别在外部条件下产生有信息量的 STR 图谱。这些数据增加了我们对影响 DNA 持久性的外部因素的理解。
