A comparison of ABAcard® Hematrace® and RSIDTM-Blood tests on dried, diluted bloodstains treated with leucocrystal violet or luminol

Abstract

Presumptive tests for blood, such as luminol and leucocrystal violet (LCV), are often used by forensic officers when screening for latent (non-visible) or diluted bloodstains at crime scenes. Where positive reactions are observed, a confirmatory test for the presence of blood may be implemented. This study aimed to compare the efficacy of two such confirmatory tests (ABAcard® Hematrace® and RSIDTM-Blood) on dried, diluted bloodstains that were enhanced using either the Grodsky luminol formulation or LCV. Eighteen replicates per dilution (1:10, 1:100), enhancement, and confirmatory test were performed (144 bloodstains). The RSIDTM-Blood test produced false negative results for all luminol-enhanced bloodstains, regardless of dilution. This test performed slightly better for bloodstains enhanced with LCV, returning approximately 50% positive results. In contrast, the ABAcard® Hematrace® test performed well, returning positive detections for all luminol-treated bloodstains, and all but two LCV-enhanced stains (both 1:100 dilution). Significant differences were observed between the test results and suggested a potential inhibitory effect on the RSIDTM-Blood test from the Grodsky luminol formulation and, to a lesser extent, LCV. This research has demonstrated that the RSIDTM-Blood test is not a reliable confirmatory test faint or latent bloodstains enhanced with luminol or LCV.