UC Davis

When a perpetrator attacks an individual, trace evidence in the form of blood may become attached to a worn garment. However, if the perpetrator wears a garment containing water-repellent properties, blood evidence may not be apparent. The blood evidence may become further undetected if the fabric is laundered in a washing machine, which is what perpetrators may try to get rid of incriminating evidence. To model this scenario, I conducted an experiment to determine if synthetic blood on water-repellent-coated and uncoated cotton and cotton/polyester blend fabric samples can be detected using visual examinations. These examinations included four presumptive blood tests – Kastle-Meyer (KM) Test, Luminol, Leucocrystal Violet (LCV), and Hemascein – that were used on samples before and after being laundered. The results of the tests varied from sample to sample, but most were successful in detecting the blood on the coated and uncoated fabric samples before and after laundering. All tests performed exceptionally for all coated and uncoated samples before being laundered by indicating a positive result for the detection of blood. For the post-laundered samples, however, Luminol and Hemascein were the only tests that showed positive results for blood on both coated and uncoated cotton and cotton/polyester blend fabric samples. The KM test and LCV tests that were either negative or inconclusive on both the coated and uncoated samples after being laundered. Further testing should be conducted in different environments and among different researchers to achieve a greater sample population for more precise results. If further results are consistent with these findings, caution should be taken when utilizing these tests to analyze potential evidence in criminal cases.