Page 8 - Patterns of Murder Blood Spatter

Pre-Lab

Solutions

Background Procedure

1. What is the first step in characterizing a 6. At what angles and heights will you drop
bloodstain pattern? blood? How many sheets of drops will you
The investigator must take a macroscopic look have at the end?
at everything in the scene. Angles: 90 °, 80 °, 60 °, and 40°. Heights: 30
cm, 60 cm, 120 cm, and 150 cm. 8 sheets.

2. What does a medium-velocity blood stain look like?
Medium velocity stains are characterized by 7. When measuring the width and length of
small, but still easily identifiable, droplets. blood droplet, which will be longer?
The length will always be longer.

3. What type of objects might cause wounds
with low, medium, and high impact patterns? 8. When stringing a crime scene or crime scene
Answers will vary. Low: knife stab, garrote, a model, what does the string’s intersection
foot splashing in a blood pool. Medium: knife indicate?
slash, baseball bat, punch. High: gunshot The strings will intersect at or around the origin
wound, machinery. of the blood spray.

4. In Blood Stain Pattern Analysis, what is 9. Why is it, or is it not, important to know the
indicated by a void? scale of the crime scene photos?
An object or person was present that blocked When constructing the model, the scale of the
the spray of blood. photos is needed to know where to position
the crime scene photos. When measuring the
width/length ratio of blood drops, the scale is
5. If you were studying a bloodstain on a flat unimportant because you are interested in a
surface, what are the shapes of droplets you ratio and not an absolute measure.
will observe? What do they indicate?
Circle and ellipse. Circle indicates that the blood
impacted perpendicular to the surface; an ellipse
indicates an impact at some angle other than 90 °.

8 THE MYSTERY OF LYLE AND LOUISE