Development of forensic blood substitute: Focusing on luminol reaction functionality

Bloodstain pattern analysis (BPA) is essential for reconstructing crime scenes using the shape and distribution of bloodstains. Luminol, which emits blue light in a chemiluminescent reaction with hemoglobin, is commonly used to detect latent blood. Artificial blood substitutes, designed for luminol reactivity or bloodstain pattern reproduction, are widely used in forensic experiments. These artificial blood substitutes, including synthetic and spatter blood, are commercialized with distinct functionalities: luminol reactivity and bloodstain pattern reproduction, respectively. This study introduces a new blood substitute that combines both functionalities. In this study, we verified the luminol reaction functionality of a newly developed forensic blood substitute, which also demonstrates bloodstain pattern reproduction capabilities. Additionally, we assessed its morphological features by analyzing the coordinate characteristics of the area of origin in impact spatter patterns. The visual inspection, without the use of supplementary equipment, revealed that there was no noticeable difference in the luminol fluorescence reaction between the developed blood substitute and the four types of commercial synthetic blood. Furthermore, the developed blood substitute exhibited the smallest standard deviation, confirming it to be the most homogeneous and stable artificial blood substitute. Morphological analysis revealed that the new substitute closely mimics human blood, particularly in z-axis coordinates. These findings establish the substitute as a versatile tool for forensic analysis, enhancing both luminol detection and bloodstain pattern reproduction.