End User Commentary on Bioanalytical Advancements in the Reliable Visualization and Discrimination of Bodily Fluids

Abstract

With the increasing sensitivity of DNA analytical methods such as DNA17 and DNA24, and the implementation of advanced software to help interpret complex mixtures of DNA from multiple persons, forensic science has never been better placed to address the ‘who’. However the challenge now for the forensic practitioner is that the sensitivity of DNA analysis is so great that it far outstrips the capability of the more rudimentary methods that identify the ‘what’. The screening methods used to initially search a crime scene or items at the laboratory so that stains can be visualised, and the subsequent tests used to confirm the body fluid type in the stains, have in many ways not evolved significantly over several decades. As the authors describe, current searching methods rely heavily on meticulous visual searching of the crime scene or items in the laboratory, supplemented by low magnification stereomicroscopy and alternative light sources, to identify stains that can then be tested chemically or microscopically to confirm the body fluid. Where the stains are more visually challenging to find, the tests instead rely on chemical screening methods that involve directly spraying chemicals on the suspect surface (for example a carpet or item of clothing), or chemically testing filter paper that has been speculatively rubbed over or blotted onto a garment.