Active oxygen doctors the evidence
Investigation at the scene of a crime begins with the search for clues. In the case of bloodstains, the most frequently used reagents are luminol and reduced phenolphthalein (or phenolphthalin that is also known as the Kastle–Meyer colour test). The limitations of these reagents have been studied and are well known. Household cleaning products have evolved with the times, and new products with active oxygen are currently widely used, as they are considered to be highly efficient at removing all kinds of stains on a wide range of surfaces. In this study, we investigated the possible effects of these new cleaning products on latent bloodstains that may be left at a scene of a crime. To do so, various fabrics were stained with blood and then washed using cleaning agents containing active oxygen. The results of reduced phenolphthalein, luminol and human haemoglobin tests on the washed fabrics were negative. The conclusion is that these new products alter blood to such an extent that it can no longer be detected by currently accepted methods employed in criminal investigations. This inability to locate bloodstains means that highly important evidence (e.g. a DNA profile) may be lost. Consequently, it is important that investigators are aware of this problem so as to compensate for it.
KeywordsCrime scene investigation Bloodstains Presumptive test Haemoglobin test
- Castelló A, Alvarez M, Miquel M, Verdú F (2002) Development of latent stains: effectiveness of luminol and evaluation of its effect on DNA analysis. Cuad Med Forense 28:33–36, [article in Spanish]Google Scholar
- Higaki RS, Philp MS (1976) A study of the sensitivity, stability and specificity of phenolphthalein as an indicator test for blood. Can Soc Forensic Sci J 9(3):97–102Google Scholar
- James SH, Eckert WG (1999) Interpretation of bloodstains evidence at crime scenes, 2nd edn. CRC Press, New YorkGoogle Scholar
- Jones CW (1999) Applications of hydrogen peroxide and its derivatives. Royal Society of Chemistry, UKGoogle Scholar
- Proescher F, Moody AM (1939) Detection of blood by means of chemiluminescence. J Lab Clin Med 24:1183–1189Google Scholar