School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3220, Australia; Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department, Macleod, VIC 3085, Australia.
Office of the Chief Forensic Scientist, Victoria Police Forensic Services Department, Macleod, VIC 3085, Australia; School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia.
Forensic Sci Int Genet. 2022 Nov;61:102765. doi: 10.1016/j.fsigen.2022.102765. Epub 2022 Aug 18.
DNA samples recovered from items of clothing are often attributed to the wearer and one or more individuals who may have contacted the item during an alleged criminal activity. Another scenario often proposed by defence counsel is that DNA was transferred from a previously contacted item/surface unrelated to the activity of interest onto the item of clothing. Under such scenarios, DNA may also be transferred from the clothing to the item/surface with which it comes into contact. One such surface is flooring, upon which clothing may be placed while not being worn or may be contacted during wearing, such as falling or being forced to the ground. This study investigates the transfer of DNA to and from clothing and flooring when different contacts are applied between the two surfaces in an environment representative of what investigators would encounter in routine casework, a residential environment. Participants were provided with two sets of new and unused upper and lower garments to wash then wear for ~8 h inside their own home before storing them in paper evidence bags. The two sets of clothing were taken to a home occupied by unrelated individuals, where one set was placed on the floor ('passive') by the researcher while the other was worn by the participant who laid with their back on the floor, rolled to one side and back, then stood up ('active'). Within the houses sampled, the main bedroom was targeted as flooring types and histories of use were more consistent across houses and less variation in DNA profile composition was previously observed for samples collected in the same room. Samples were collected from predetermined areas of the clothing and flooring where contact did and did not occur. Reference profiles were obtained from wearers and individuals they lived with, as well as occupants of the home. DNA transfer was observed from clothing to flooring and from flooring to clothing in both 'active' and 'passive' situations, though greater where a situation involved the application of pressure and friction ('active'), and only where contact between clothing and flooring occurred. Results from this study inform on the composition of DNA profiles one is likely to obtain from an item of clothing or a flooring surface following a similar contact event between the two substrates and will aid investigators when interpreting DNA evidence recovered in a domestic environment and the activities leading to its transfer and subsequent recovery.
从衣物上提取的 DNA 样本通常归因于穿着者和一个或多个在涉嫌犯罪活动中可能接触过该物品的人。辩护律师经常提出的另一种情况是，DNA 是从与所关注活动无关的先前接触过的物品/表面转移到衣物上的。在这种情况下，DNA 也可能从衣物转移到与之接触的物品/表面上。一个这样的表面是地板，当衣物不穿或在穿着时接触到地板，例如摔倒或被迫倒地时，衣物可能会放在地板上。本研究调查了当两个表面在代表调查人员在常规案件工作中遇到的环境中进行不同接触时，DNA 在衣物和地板之间的转移情况，一个居住环境。参与者提供了两套新的未使用的上下衣，然后在家中穿着大约 8 小时，然后将其存放在纸质证据袋中。两套衣服被带到一个与无关人员居住的家中，一套由研究人员放在地板上（“被动”），另一套由参与者穿着，他们背部靠在地板上，向一侧滚动，然后站起来（“主动”）。在所采样的房屋中，主卧室被确定为地板类型，并且房屋之间的使用历史更为一致，并且在同一房间收集的样本中观察到 DNA 谱组成的变化较小。从衣物和地板的预定区域收集样品，这些区域发生了和未发生接触。从穿着者和与其一起生活的人以及房屋的居住者那里获得参考谱。在“主动”和“被动”情况下，均观察到 DNA 从衣物转移到地板，从地板转移到衣物，但在涉及施加压力和摩擦力的情况下（“主动”）更多，并且仅在衣物和地板之间发生接触的情况下。本研究的结果提供了有关在两个基材之间发生类似接触事件后，从衣物或地板表面获得的 DNA 谱组成的信息，并在解释在家庭环境中回收的 DNA 证据以及导致其转移和随后回收的活动时为调查人员提供帮助。
