Validation of an immunochromatographic D-dimer test to presumptively identify menstrual fluid in forensic exhibits.

Identifying the biological source of a crime scene stain can be crucial for police investigations in many scenarios. Blood is one of the most common fluids found, and accurate differentiation between peripheral blood and menstrual fluid could provide valuable information regarding the issue of consent in sexual assault cases. For the detection of menstrual fluid, no easy-to-use presumptive test is available to date. Therefore, this study aimed to validate a simple immunochromatographic test for the indication of menstrual fluid, focusing on a D-dimer assay. The Clearview® rapid D-dimer test provides a diagnostic assay for the detection of fibrin degradation products. We validated the sensitivity and robustness of the assay using fresh and dried menstrual fluid samples, body fluid mixtures, diluted samples, and casework swabs. Cross reactivity was tested for saliva, semen, vaginal fluid, and blood. No false positive results were obtained; it was possible to successfully analyze mixtures, highly diluted samples, and casework swabs. The results of this study indicate that the D-dimer assay reliably detects menstrual fluid in forensic exhibits and is easy to implement into the current workflow of body fluid identification.

Independent validation of body fluid-specific CpG markers and construction of a robust multiplex assay.

Potential forensic use of tissue-specific DNA methylation markers has recently been discussed for the identification of the biological source of a stain. In this study 13 promising markers were evaluated to identify suitable candidate markers for the development of a robust and reliable multiplex assay. The results of this study suggest that a combination of only four highly informative markers will be enough for clear body fluid identification. A multiplex assay was developed for the identification of menstrual blood, saliva, semen, and venous blood. This assay was successfully applied to the identification of these body fluids in mixtures and crime scene stains. The multiplex assay aids in the identification of not only single source body fluids but also of body fluid mixtures. The main advantage of using DNA methylation assays over alternative tests is that it can be applied at a later time point in the investigative process since testing is possible even after DNA analysis.