Physical evidence Flashcards
Glass, Bullets, Blood, Seeds/Pollen, and Tracks/soil
What does the hematocrit level measure?
A hematocrit (he-MAT-uh-krit) test measures the proportion of red blood cells in the blood. Red blood cells carry oxygen throughout the body. Having too few or too many of them can be a sign of certain diseases.
Explain the differences between a presumptive and confirmatory test.
A presumptive test is a chemical test which, by the production of color or light, indicates the presence of a body fluid. It is typically more sensitive and less specific than a confirmatory test. A confirmatory test is a test that verifies the presence of a specific compound.
One presumptive test and one confirmatory test used to detect the presence of blood.
The presumptive test used for the detection of blood in the FBU is the Hemastix test from Miles Laboratories. The test consists of a plastic strip with a reagent-treated filter paper tab at one end. The tab contains Tetramethylbenzidine (TMB), diisopropylbenzene dihydroperoxide, buffering materials, and non-reactants.
The confirmatory test used to confirm human blood in the FBU is RSID-Blood, an immunological-based test, provided by Independent Forensics. RSID-Blood is an antigen-antibody test, using glycophorin A found in the red blood cells.
