This research tests the effectiveness of six common household cleaning products on the removal of dried blood deposits. Two presumptive tests were used – Kastle-Meyer (KM) and luminol. The cleaning products tested were: Ariel Excel Gel with Actilift Biological; VANISH Oxi Action Powerspray Carpet & Upholstery Stain Remover; Flash Bicarbonate of Soda All Purpose Spray; Cilit Bang Power Cleaner Bleach and Hygiene; Pink Stuff Cleaning Paste; Dettol Power and Fresh Spray Citrus. Selected to fit the scenario of the thesis –in the situation where popular brands accessed by a member of the public, and by inexperienced individuals that attempt to clean up the scene of violent crimes. Blood was deposited on seven separate carpet tiles; each was cleaned with a corresponding cleaning product. Each tile was intensively cleaned with a scrubbing sponge for a total of three minutes. The positive control in this research was the tile that was not cleaned, which can be compared to the other results. In this research the level of chemiluminescence that was produced from the luminol test correlates to how effective the cleaner was –the less the carpet luminesced by glowing blue the more effective the cleaner was considered. Many studies have explored the phenomena of false positive and false negatives arising from the application of luminol onto surfaces cleaned with bleach. A false positive or negative result is when the presumptive test reacts in a way to produce a result that wrongly indicates that a particular condition or attribute is present, in this case the presence of blood. In this research, a false negative may arise if the presumptive test results for KM or luminol are negative even when the blood deposits are visible. A cross-comparison of the results from both tests indicated that none of the six cleaners were successful at removing all traces of the blood. The KM testing that was completed before and after cleaning, for all tiles, had positive results. The luminol test that was performed on each tile subsequent to cleaning also showed significant chemiluminescence – all positive results. Even with all the presumptive tests resulting as positive, the stains left after cleaning were all visually apparent and if found on the scene would certainly be tested from observational suspicion alone. Of the six products, Dettol and Flash appeared to move the biological material the most but they failed in many regards, as they still produced consistent positive results. It was concluded that of all the cleaners none were substantial enough to be classed as effective at removal of dried blood deposits.
Keywords: Forensic science, Blood, cleaning products, chemiluminescent, luminol, Kastle-Meyer, presumptive testing, crime scene investigation.
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