Conventional methods

Another method for body fluid identification that has seen recent research activity is the monitoring of cell-specific gene expression through the analysis of ribonucleic acid (RNA). Conventional methods for body-fluid identification often involve labor-intensive, diverse approaches that are performed sequentially rather than simultaneously. Both time and sample are lost when many of these older characterization assays are performed. Research on RNA techniques has shown that although less stable than DNA (due to its single stranded structure and often rapid destruction from digesting enzymes), RNA is able to help with stain identify cation. Multiple RNA transcripts have been detected with reverse transcriptase PCR followed by gel or capillary electrophoresis or real-time PCR. Blood, semen, saliva, menstrual blood, and vaginal secretions have been simultaneously identified with some of these assays. The quantitation of RNA degradation has also been used in an effort to determine postmortem intervals and to determine the age of bloodstains.
Sources:
Anderson , S. , et al. ( 2005 ) . A method for determining the age of a bloodstain. Forensic Science International, 148 , 37 – 45 . Bauer , M. ( 2007 ) . RNA in forensic science . Forensic Science International: Genetics , 1 , 69 – 74 . Juusola , J. , & Ballantyne , J. ( 2003 ) . Messenger RNA profi ling: A prototype method to supplant conventional methods for body flu identification. Forensic Science International, 135 , 85 – 96 . NoreaultConti, T. L., &Buel, E. (2008) Development of an RNA-based screening assay for forensic stain identification. In: Proceedings of the 19th international symposium on human identification. Available at http://www.promega.com/geneticidproc/ussymp19proc/oralpresentations/Buel.pdf