Evaluation of genetic markers for forensic identification of human body fluids

Identification of body fluids deposited at crime scenes can often become challenging due to their small size, poor visibility to the naked eye and the effect of environmental insults. Traditionally, body fluids are identified using techniques that are enzyme-based, non-specific, require large amount of samples, prone to contaminations and not available for all body fluids. These techniques are presumptive and mostly require confirmatory tests. New techniques of body fluid identification have emerged over the last decade and are still on the rise. In this study, highly specific genetic markers (mRNA) were used to identify four commonly encountered forensic body fluids which include blood, semen, saliva and vaginal secretion. A 14-marker mRNA multiplex based assay was developed and validated. All markers were expressed in their target body fluids with no cross reactions in non-target body fluids. The unambiguous identification of the four body fluids with this assay further established its compatibility with forensic laboratory workflows.