In conclusion, neither luminol nor Bluestar® affect the results of PT or TMB tests at blood dilutions equal to or less than 1:100 and there were substrate differences seen with blood dilutions 1:1000 or greater. In some test scenarios, luminol and Bluestar® appear to potentiate the effects of PT and TMB (cement block) and Bluestar® attenuates the effects TMB (clothing) at a blood dilution of 1:1000. Bluestar® was the only presumptive test that can detect blood dilutions of 1:100,000 on some substrates and luminol was inclusive on treated wood. These findings suggests that forensic science laboratory personal need to know and understand the details of how the blood was detected by the crime scene investigator and the substrate on which the blood was obtained from in their preparation for presumptive blood testing with PT or TMB.