Which test must be used to confirm blood evidence in the laboratory?

• A. Hemastix
• B. A presumptive field test
• C. A confirmatory test
• D. A screening test

Answer: (C)

In forensic blood analysis, you start with a screening (presumptive) test to flag possible blood but it isn’t definitive. Hemastix is one such presumptive test; it can react with substances other than blood and doesn’t prove its presence. To verifiably establish that blood is present in the sample, a confirmatory test is required. This type of test uses more specific methods or reagents in order to definitively identify blood (and, if needed, human blood), reducing false positives from screening tests. Examples of confirmatory approaches include tests like Takayama or Teichmann for hemoglobin or immunoassays that target human blood.