ABSTRACT
This chapter focuses on biology evidence screening and advances in deoxyribonucleic acid (DNA) profiling technology. The most desirable presumptive test is one that is specific, sensitive and will not hamper the extraction or subsequent amplification of DNA. To date, most biological evidence screening methods are cost effective and rapid but unfortunately the tests are often inefficient and nonspecific. Analysis of suspected seminal stains is usually initiated by carrying out presumptive biochemical tests for substances characteristically found in the body fluid. The mechanism of reaction for all presumptive catalytic tests for blood is based on the peroxidase-like activity of hemoglobin and a number of its derivatives. Many advances in microscopic instrumentation have allowed new methods of spermatozoa detection and separation to be introduced. The Christmas Tree stain is one of the most commonly employed staining techniques in forensic laboratories and provides excellent morphological detail and good discrimination between sperm cells and epithelial cells.
