Chapter 15: Forensic Serology: Blood & Biological Evidence

The text explores immunoassay techniques, such as the Enzyme-Multiplied Immunoassay Technique (EMIT), which utilize drug-protein complexes to detect substances of abuse in urine, and distinguishes between polyclonal and monoclonal antibodies. A significant portion of the chapter is dedicated to the forensic characterization of bloodstains, detailing the protocol for answering three critical questions: is it blood, is it human, and to whom does it belong. This includes presumptive color tests like the Kastle-Meyer (phenolphthalein) reaction and Hemastix, as well as chemiluminescent reagents like Luminol and Bluestar that reveal latent blood patterns without destroying DNA. Confirmatory microcrystalline tests (Takayama and Teichmann) and species-determination methods like the precipitin test, gel diffusion, and electrophoresis are also covered. The chapter reviews the principles of heredity, explaining concepts such as genes, chromosomes, alleles, homozygosity versus heterozygosity, and how Punnett squares can predict genotypes and phenotypes in paternity disputes. Furthermore, the text addresses the forensic analysis of semen in sexual assault investigations, describing the acid phosphatase color test for locating stains, microscopic identification of spermatozoa, and the detection of Prostate Specific Antigen (PSA or p30) for cases involving oligospermia or aspermia. Finally, the chapter outlines rigorous protocols for the collection and preservation of rape evidence, emphasizing the importance of paper packaging to prevent mold, the collection of reference samples, and the timeline of sperm survival within the victim to assist in reconstruction.