The efficacy of luminol in detecting bloodstains that have been washed with sodium percarbonate and exposed to environmental conditions

Abstract

Blood evidence has a highly valuable role to play in crime investigation and crime reconstruction both in terms of DNA evidence and bloodstain pattern analysis (BPA). This paper presents the results of experiments that were designed to investigate the persistence and detectability of blood on clothing when exposed to different conditions and when washed in conjunction with sodium percarbonate (also known as active oxygen). Previous studies have demonstrated that the removal of traces of blood from denim and carpet is improved by the addition of sodium percarbonate, when compared with washing with detergent alone. In exploring this issue further, this study confirms that the efficacy of sodium percarbonate in removing bloodstains depends on the temperature of the wash cycle, the type of detergent used, drying time of blood and exposure of bloodstains to environmental conditions. The implications for the interpretation or blood evidence are considered, while the importance of continuing to develop an evidence base for the interpretation of blood evidence is emphasized.