The impact of accelerant facilitated fire on blood detection and the efficacy of subsequent soot removal methods

Previous literature has established that recovering heat damaged body fluids is possible, however with little investigation into the effect of accelerants used in initiating arson fires. This study therefore aimed to determine whether presumptive blood detection was affected by heat damage resulting from accelerant facilitated fires. Another objective was to examine various techniques for removing soot, which is a noted barrier to blood detection. The study focused on blood deposited on household flooring materials, one porous and one nonporous surface: carpet and tile respectively. Samples were burned with butane, petrol, and kerosene then presumptively tested using the Kastle Meyer colourimetric blood detection test. Testing was then repeated following soot removal by either wiping, scraping, or using liquid latex. The “strength” of positive detections was evaluated using a scale based on reaction speed and colour intensity. Results demonstrated that accelerants weakened detection strength, although nearly all samples tested positive overall, and the impact of each accelerant on both surface types was largely similar. It was also discovered that soot removal improved the strength of blood detection results in approximately 69% of carpet and 47% of tile samples, with wiping being the superior method on both surface types. Consequently, introducing this investigative step may be critical to maximizing blood evidence recovery in arson casework. These findings indicate the worth in recovering severely burned items, particularly for evidence as crucial as blood.