Page 9 - Stained With Suspicion Blood Detection
P. 9
Pre-Lab
Solutions
1. What are the two major components of 5. How do investigators find bloodstains that are
blood? not immediately visible under normal lighting
The two major components are plasma and They use chemicals, such as Luminol or
formed elements (cells and cell fragments). Flourescein.
2. What test did forensic scientists use to link 6. Why are presumptive tests performed before
blood to an individual until the 1990’s? confirmatory tests?
ABO blood grouping Presumptive tests are more cost-efficient, and
they can be done easily and quickly at the crime
scene by a police officer on site.
3. What test is now used extensively to link
blood to an individual?
DNA profiling or DNA typing. 7. If a presumptive test has a positive result, can
investigators guarantee that blood is present?
No, if a test is positive, blood is probably
4. Why are blood detection tests still important present; however, there are some elements that
in current investigations? can cause false positives.
Investigators need to know whether blood is
present, or has been present, at a crime scene. This
is important for recreating the events of a crime.
THE MYSTERY OF LYLE AND LOUISE 9
