A Quantitative Method for Determining a Representative Detection Limit of the Forensic Luminol Test for Latent Bloodstains

The luminol test has been used for just over 60 years by forensic investigators for presumptive identification of blood and visualization of blood splatter patterns. Multiple studies have estimated the limit of detection (LD) for bloodstains when luminol is used, with results ranging from 100 to 5,000,000 dilute; however, these studies typically have not identified and controlled important experimental variables that may affect the luminol LD for bloodstains. Without control of experimental parameters in the laboratory, variables that affect the potential of presumptive bloodstain test methods remain largely unknown, and comparisons required to establish new, more powerful detection methods are impossible. The method developed in the current project resulted in an estimated LD for bloodstains on cotton fabric at 200,000 diluted blood with a specific luminol formulation. Although luminol is the focus of this study, the experimental protocol used could be modified to study effects of variables using other blood detection reagents. (publisher abstract modified)