Page 28 - Patterns of Murder Blood Spatter

6. Use a pushpin to secure an end of string to the 12. Measure to the center of each of the areas of
center of each selected blood spot. impact, along the x, y, and z axes (as shown in
the figure above). Record the measurements in
7. Hold a protractor to the model wall so that it is the “Lab3a Data” worksheet.
centered on the end of the string.
3b. Determining Height of Drops
8. Using the protractor, pull the string out so
that it runs in the direction of travel, and at the 1. Open the “Lab3b Data” worksheet in the
appropriate angle as generated by the “Lab3a spreadsheet. Replace the formulas in column E
Data” worksheet. with the equation derived in “Height vs. Width”
chart. Replace the “x” in the formula with the
9. Attach the free end of the string to the appropriate cell in column B.
base of the model with a piece of tape do
not use the push pins to attach the string to 2. Examine blood spatter image D. This is a 1:1
the base. scale image of the trail of drops from the male
victim to the female victim, therefore the
10. Repeat steps 6-9 for each of the drops measurements do not need to be adjusted.
circled. If a drop is not able to be measured
easily, or if the string is too short to mount 3. Measure the length and width of drops in the
to the base, choose a different photo. Record these values in the gray shaded
blood drop. cells in the “Lab3b Data” worksheet.

11. After placing the strings, they should converge 4. The spreadsheet will have generated the
in one, two, or three areas. These areas are the estimated height from which the blood
locations of impact. drops fell.

28 THE MYSTERY OF LYLE AND LOUISE