School of Molecular and Life Sciences, Curtin University, GPO Box U1987, Perth, Australia.
ANSTO, Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, Australia.
Analyst. 2022 Jan 31;147(3):387-397. doi: 10.1039/d1an01951a.
In forensic science, knowledge and understanding of material transfer and persistence is inherent to the interpretation of trace evidence and can provide vital information on the activity level surrounding a crime. Detecting metal ions in fingermark residue has long been of interest in the field of forensic science, due to the possibility of linking trace metal ion profiles to prior activity with specific metal objects ( gun or explosive handling). Unfortunately, the imaging capability to visualise trace metal ions at sufficient spatial resolution to determine their distribution within a fingermark (micron level) was not previously available. Here, we demonstrate for the first time transfer and persistence of metals in fingermarks, at micron spatial resolution, using synchrotron sourced X-ray fluorescence microscopy. Such information may form a critical baseline for future metal-based detection strategies. Fingermarks were taken before and after brief handling of a gun barrel, ammunition cartridge case and party sparkler to demonstrate the transfer of metals. The results reveal increased metal content after contact with these objects, and critically, a differential pattern of metal ion increase was observed after handling different objects. Persistence studies indicate that these metals are removed as easily as they are transferred, with a brief period of hand washing appearing to successfully remove metallic residue from subsequent fingermarks. Preliminary work using X-ray absorption near edge structure spectroscopic mapping highlighted the potential use of this technique to differentiate between different chemical forms of metals and metal ions in latent fingermarks. It is anticipated that these findings can now be used to assist future work for the advancement of trace metal detection tests and fingermark development procedures.
在法医学中，对物质转移和持久性的了解和认识是解释微量物证的固有内容，并且可以为犯罪活动周围的活动水平提供重要信息。由于有可能将痕量金属离子分布与特定金属物体（枪支或爆炸物处理）的先前活动联系起来，因此长期以来，法医学领域一直对检测指痕中的金属离子感兴趣。不幸的是，以前没有足够的空间分辨率来可视化微量金属离子以确定其在指痕（微米级）内分布的成像能力。在这里，我们首次使用同步加速器源 X 射线荧光显微镜演示了在微米空间分辨率下金属在指痕中的转移和持久性。这些信息可能成为未来基于金属的检测策略的重要基准。在简要处理枪管、弹药筒和派对烟花后，采集了指印，以证明金属的转移和持久性。结果表明，与这些物体接触后金属含量增加，而且处理不同物体后观察到金属离子增加的模式存在差异。持久性研究表明，这些金属与转移一样容易被去除，短暂的洗手似乎可以成功地从后续指印中去除金属残留。使用 X 射线吸收近边结构光谱测绘进行的初步工作强调了该技术在区分潜伏指印中不同化学形式的金属和金属离子方面的潜在用途。预计这些发现现在可用于协助未来的微量金属检测试验和指印开发程序的改进工作。
