Why Do Sloots Use Presumptive Tests Important In Forensics?

The analysis done by Sloots et al. not only makes a major contribution to the field of forensics, but provides alternatives and new starting points for forensic investigators and researchers. Body fluids, such as blood, are one of the most common types of physical evidence found at crime scenes and have the ability to identify individuals involved in a crime and exclude others (9). It is important, however, for investigators to know the identity of a body fluid, in order to preserve it properly for later DNA analysis; presumptive tests make this possible (5). Presumptive tests are used as a first assessment of physical evidence (5) and are quite beneficial in forensics seeing as they are efficient, easy to use, and cost-effective (9). A negative result from a presumptive test can help to steer investigators away from a piece of evidence, while a positive presumptive test is an indication for investigators to

reveals that the presumptive KM direct-test, that has been in use in the forensic identification field for decades, lowers the overall yield of DNA, and thus interferes with DNA analysis of stains containing minimal blood to begin with (2). This revelation is important for forensic labs, such as the Centre of Forensic Sciences (CFS), which use this test to identify diluted stains as blood, and then attempt to generate DNA profiles from them (2). In the introduction of the article, the authors stated that the CFS rarely obtained DNA profiles of good quality–if any was obtained at all– from samples tested using the KM direct-test (2). This is a complete waste of time as well as resources, seeing as DNA analysis is a very involved process with multiple steps (8). First it requires extraction of the DNA from the body fluid of interest via organic extraction, using alcohol and phenol/chloroform (10), or inorganic extraction (2). The DNA then needs to be quantified via qPCR using technology such as the Plexor® HY System (2) or Quantifiler® Duo