To test or not to test for body fluids: integration of body fluid identification and direct PCR in one workflow

Frequently at crime scenes, it is possible to find lesser amounts of biological material, which prevents performing all the analyses to make a full identification of the evidence: body fluid identification, DNA extraction, human DNA quantitation, and short tandem repeats (STR) profiling. In these situations, DNA profiling is chosen over body fluid identification. Nowadays, the current advancements in forensic genetics, such as the development of different swab materials and direct polymerase chain reaction (PCR) amplification, allow us to skip the steps of DNA extraction and quantitation, avoiding losing important amounts of genetic material and original evidence. However, DNA profiling is as important as body fluid identification in certain cases. The present study assessed the efficiency of integrating body fluid identification by immunochromatographic tests and genetic profiling into a single workflow using microFLOQ® swabs and evaluating different approaches in bloodstain samples. The findings from this research indicated that the microFLOQ can be used both for sampling directly from the source and for subsampling from swabs of different materials, followed by direct PCR to get good-quality STR profiles, in this case allowing to extract the maximum information from a "unique" source of evidence before destruction, as in body fluid and genetic identification. Future research can expand these results to other body fluids (i.e., semen and saliva) and mixtures. Key points  The present work showed that the integration of body fluid identification by immunochromatographic tests and genetic profiling by STR analysis into a single workflow is feasible.Three different strategies for integrating body fluid identification and genetic profile into one single workflow were assessed with different results.No clear correlation was found between hemoglobin concentration and the quality of the STR profiles.A viable solution for low-quantity DNA casework scenarios may be using microFLOQ for subsampling from regular cotton or nylon-flocked (4N6FLOQ) swabs.