Moore David, Beaumont Dan, Brown Melanie, Clayton Tim, Coleman Kiera, Subhani Zuhaib, Thomson Jim
Eurofins Forensic Services, Teddington, UK.
Eurofins Forensic Services, Teddington, UK.
Sci Justice. 2021 Mar;61(2):160-169. doi: 10.1016/j.scijus.2020.11.002. Epub 2020 Nov 19.
Cartridge cases are often recovered from crime scenes involving firearms and, in the United Kingdom (where gun possession is strictly controlled), these are commonly from 9 mm calibre ammunition. The ability to obtain informative DNA profiles from touch DNA on recovered cartridges could have a significant impact on the investigation of that type of offence. However, this avenue may not be routinely considered as investigators in the UK have historically had a low expectation of obtaining useful DNA profiles. This stance may not be unreasonable given that (a) only trace amounts of DNA are likely to have been transferred onto the cartridge cases through handling; and (b) when the cartridge is spent, the potential deterioration of that DNA caused by the act of discharging the weapon. We introduce a novel semi-automatable method using direct lysis for the recovery of DNA from ammunition and compare it with a traditional double-swabbing method (using wet and dry swabs). DNA profiling of the DNA recovered using both methods was carried out using the ESI17 FAST STR system (Promega). This demonstrated a significant increase in DNA recovery using the direct lysis approach, and correspondingly improved STR results. We also investigated the effect on the recovery and profiling of DNA from fired, and unfired, 9 mm cartridges using the direct lysis technique. These results demonstrate that DNA suitable for STR analysis can still be recovered from fired ammunition with only slightly reduced yields compared to unfired ammunition. In these experiments, the handler of the ammunition was most commonly either the sole contributor or the major contributor to the recovered DNA profile.
弹壳常常从涉及枪支的犯罪现场找到，在英国（枪支持有受到严格管控），这些弹壳通常来自9毫米口径弹药。从找回的弹壳上的接触性DNA获取信息丰富的DNA图谱的能力，可能会对这类犯罪的调查产生重大影响。然而，这条途径可能不会被常规考虑，因为英国的调查人员历来对获得有用的DNA图谱期望不高。考虑到以下两点，这种立场可能并非不合理：（a）通过处理，只有微量的DNA可能已转移到弹壳上；（b）当子弹发射后，武器发射行为可能导致DNA的潜在降解。我们介绍一种使用直接裂解从弹药中回收DNA的新型半自动方法，并将其与传统的双擦拭法（使用湿拭子和干拭子）进行比较。使用这两种方法回收的DNA的DNA图谱分析是使用ESI17快速STR系统（普洛麦格公司）进行的。这表明使用直接裂解方法可显著提高DNA回收率，并相应改善STR结果。我们还研究了使用直接裂解技术对已发射和未发射的9毫米弹壳上DNA回收和图谱分析的影响。这些结果表明，与未发射的弹药相比，从已发射的弹药中仍可回收适合STR分析的DNA，产量仅略有降低。在这些实验中，弹药的处理者最常是回收的DNA图谱的唯一贡献者或主要贡献者。
