Abstract:
The use of RNA to identify body fluids is becoming a common practice in forensic investigations. As this method develops, it is important to consider how everyday activities can affect the ability to detect body fluids that are relevant to the investigation. This can either be through further degradation (as forensic samples themselves are often poor quality) or detection of background body fluids irrelevant to forensic investigations. This research investigates the transfer and persistence of different body fluids during laundering, and the detection of background levels of body fluids on commonly used surfaces. There has been little research on this previously, with the majority of the investigations focusing on DNA rather than RNA. The transfer and persistence of the body fluids during laundering was investigated by staining three pairs of underwear with five body fluids of interest, circulatory blood, saliva, semen, vaginal secretions and menstrual blood, and laundering them together. Following the laundering the underwear was sampled via minitaping and fabric cutting. To investigate the background levels of body fluids in the environment minitape samples were taken from a variety of different surfaces and objects commonly located in offices and homes. The RNA was then extracted from these samples and analysed using the CellTyper and CellTyper II multiplexes in order to detect the biomarkers for the body fluids of interest. Massively parallel sequencing was also performed on the laundering samples but the concentration of RNA proved too little for sequencing and as a result, no meaningful results were obtained using this method. This research found that body fluids persisted after laundering and that some body fluids were also found to have transferred between the clothing samples during the laundering process. The investigation of body fluids background levels in the environment showed that saliva was found the most frequently, although some other body fluids were detected. This study demonstrated that everyday activities such as laundering and background levels of body fluids need to be taken into consideration when analysing body fluids detected via RNA. This work is preliminary but provides a strong foundation for the expansion and development of future studies.