DNA degradation in biological material needs to be better understood. Bloodstains on washed clothing are disturbed by washing procedures, sometimes transferred to other fabrics, often with latent bloodstains and usually with significantly degraded DNA. The samples (cotton fabric with bloodstains) are divided into six main groups, depending on the washing method regarding water temperature (95, 60, and 30 °C) and the detergent use. After completing the washing process, samples were stored for a certain period (1 day to 6 months) and subsequently analyzed. Analyses were performed using standard protocols and commercial kits to measure the remaining DNA quantity (concentration) and DNA degradation index in the processed samples. Our results revealed that the high washing temperature (60 and 95 °C) and the application of detergent have a synergic action on DNA degradation, while at 30 °C this effect is absent. Furthermore, the effect of detergent on accelerated DNA degradation is observed about a month after the washing. This delayed effect of detergent has no explanation in current literature data. To obtain optimal results from the bloodstains, we recommended that the period from the crime event and attempted cleaning by a perpetrator to the laboratory analysis should be less than 1 month.

需要更好地了解生物材料中的 DNA 降解。洗过的衣服上的血迹会因洗涤程序而受到干扰，有时会转移到其他织物上，通常带有潜在的血迹，并且通常带有明显降解的 DNA。根据水温（95、60 和 30 °C）的洗涤方法和洗涤剂的使用，样品（有血迹的棉织物）分为六组。完成清洗过程后，将样品保存一定时间（1天至6个月）并随后进行分析。使用标准方案和商业试剂盒进行分析，以测量处理后的样品中剩余的 DNA 数量（浓度）和 DNA 降解指数。我们的结果表明，高洗涤温度（60 和 95 °C）和洗涤剂的应用对 DNA 降解具有协同作用，而在 30 °C 时则不存在这种作用。此外，在洗涤后大约一个月观察到去污剂对加速 DNA 降解的影响。目前的文献数据中没有解释洗涤剂的这种延迟效应。为了从血迹中获得最佳结果，我们建议从犯罪事件发生和犯罪者尝试清洁到实验室分析的时间应少于 1 个月。