Redhead Paul, Brown Melanie K
Teesside University, School of Science & Engineering, Middlesbrough, UK.
Sci Justice. 2013 Jun;53(2):187-91. doi: 10.1016/j.scijus.2012.09.004. Epub 2012 Oct 4.
The ability to detect semen in sexual offence cases is a crucial first step to locating stains which may be suitable for DNA profiling. Since the development of the acid phosphatase test in the late 1950s by Stuart S. Kind, the process undertaken to perform the test has gone largely unchanged. The method currently accepted by operational forensic science laboratories allows 2 min for a reaction to be obtained, and until relatively recently, this has not been challenged. In this research, samples of semen were obtained from three donors and a range of dilutions for each sample were prepared. Each dilution was subjected to acid phosphatase testing using both direct testing and the 'press test' method. The results showed that semen could be detected in excess of 15 min in dilutions up to 1 in 400 using the press test method and in dilutions up to 1 in 1000 using the direct method. Of further significance was the observation that using the press test method, the two minute cut-off was insufficient to detect the majority of stains and in some cases, semen stains as strong as 1 in 20 dilutions. This research provides compelling evidence for protocols currently utilised in forensic practice to be reviewed in order that forensic scientists do not overlook potential evidential material that may prove suitable for body fluid identification such as DNA STR profiling.
在性犯罪案件中检测精液的能力是找到可能适合进行DNA分析的污渍的关键第一步。自20世纪50年代末斯图尔特·S·金德开发酸性磷酸酶检测方法以来，进行该检测的过程基本没有变化。目前法医科学操作实验室所采用的方法允许2分钟来获得反应，直到最近，这一点都没有受到质疑。在这项研究中，从三名捐赠者处获取了精液样本，并为每个样本制备了一系列稀释液。对每种稀释液分别使用直接检测法和“按压检测”法进行酸性磷酸酶检测。结果表明，使用按压检测法，在高达1:400的稀释液中超过15分钟仍能检测到精液，使用直接检测法在高达1:1000的稀释液中仍能检测到精液。更重要的是，观察结果表明，使用按压检测法时，两分钟的截止时间不足以检测到大多数污渍，在某些情况下，甚至无法检测到高达1:20稀释度的精液污渍。这项研究为审查目前法医实践中使用的规程提供了令人信服的证据，以便法医科学家不会忽略可能适合进行体液鉴定（如DNA STR分析）的潜在证据材料。
