<p>Body fluid samples provide crucial evidence in forensic investigations. Analyzing them typically involves two types of tests: presumptive tests for preliminary screening and confirmatory tests for definitive identification. For example, the luminol test is a widely used presumptive test for detecting latent bloodstains at crime scenes. Upon reacting with blood, luminol produces luminescence, making invisible bloodstains detectable and aiding in blood sample collection. By contrast, messenger RNA (mRNA) analysis is used as a confirmatory test. Because these tests serve distinct purposes, forensic samples screened using presumptive tests may still be subjected to mRNA-based body fluid identification. Nevertheless, the effects of presumptive tests on subsequent mRNA analyses remain unclear. In this study, we assessed the effect of the luminol test on the detection of blood mRNA marker hemoglobin β (HBB). We found that although the luminol test resulted in HBB mRNA degradation, the RNA marker remained relatively stable in bloodstains dried after luminol testing. Our findings provide insights into the stability of HBB mRNA following luminol application.</p>