A review of the techniques for the forensic investigation and differentiation of human blood and decomposition fluid stains

An important aspect of forensic science is the detection and identification of biological fluids at a crime scene (Virkler and Lednev 2009). The determination of the type and origin of a biological sample can yield valuable information that supports a link between the criminal act and donor, which in turn may assist in the reconstruction and sequencing of a crime scene (An et al. 2012). A body and therefore any associated biological stains may not be located for a period of time, during which the decedent will begin to decompose. Blood and decomposition fluid stains have been reported to be visually similar (Comstock 2014) and therefore, it is important to determine the source of the stain. The presence of blood would suggest an injury has occurred before or shortly after death, whereas decomposition fluid is produced as a part of the naturally occurring decomposition process. Several approaches including visual examination, pH measurements, presumptive testing for blood, spectroscopic techniques, the analysis of volatile organic compounds, genomics, and proteomics may provide potential methods of biological stain identification and differentiation (Harbison and Fleming 2016; Stuart 2013; Virkler and Lednev 2009). However, there are associated limitations to these methods. This dissertation reviewed the effectiveness of these methods, which then informed the development of a proof--‐of--‐ concept study to assess if the technique of microfluidic proteomics by protein electrophoresis can identify potential differences between blood and decomposition fluid stains. When compared to conventional techniques, microfluidic devices offer many advantages including improved efficiency, a decrease in sample and reagent consumption, and automation (Li 2015). The potential results obtained from the proposed study design will assist in enhancing the knowledge base surrounding the differentiation of blood and decomposition fluid stains