Blood Stain Lab
Name:_____________________________________
Scenario
The police examined the blood spatter at a crime scene. From the size of the droplets, it appeared that the blood had
passively dripped as the injured person walked across the floor. The person may have experienced a second injury,
because two different patterns of blood spatter appeared halfway across the room. The second injury seemed to be from a
source higher up on the person’s body.
By examining the size and shape of blood spatter, forensic scientists are able to reconstruct a crime emerges as the bloodspatter analysis starts to “tell the story.”
In this activity, you will experiment with dropping artificial blood from different heights, and you will make observations
about the effect of height on blood spatter.
Materials
Synthetic blood
Paper
Tile
Pipette
Metric ruler
meter stick
Clipboard
Protractor
Graph paper
Procedure
1.) Place a piece of paper on the clipboard provided. (see charts for the angle and distance you should place your
paper for each trial)
2.) Use the pipette to drop one droplet of blood onto the paper. Record any observation. Label the spatter with the
corresponding height and angle.
3.) Measure the height and width of the spatter (record in the data table.)
*Be careful with measuring, your sample will still be wet and you don’t want to contaminate your
evidence. Measure only the elliptical impact pattern not the drip mark!
4.) Position the paper to accommodate ensuing drops for the next height or angle.
5.) Continue the process, using different pieces of paper (as necessary) and different mediums, for the indicated
angles (00, 200, 400, etc...) and heights. (Floor tiles and glass)
6.) Divide the width (w) by the length (l) and record this number to the nearest 1/1000th
7.) Create two graphs for each medium.
8.) On the first graph, the x-axis represents the angle of impact and the y-axis represents the ratio of width to length
(w/l). Using different symbols or colors, plot the data for each height.
9.) On the second graph, the x-axis represents the height and the y-axis represents the ratio of width to length (w/l).
Using different symbols or colors, plot the data for each angle.
10.) Don’t forget to title your graphs
Paper
00
15cm
w=
l=
w/l=
45cm
w=
l=
w/l=
75cm
w=
l=
w/l=
105cm
w=
l=
w/l=
135cm
w=
l=
w/l=
165cm
w=
l=
w/l=
w=
l=
w/l=
w=
l=
w/l=
w=
l=
w/l=
w=
l=
w/l=
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l=
w/l=
w=
l=
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l=
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Observations
200
Observations
400
Observations
600
Observations
Repeat with Floor tiles and Glass
Post lab
1.) Is there a relationship between the height from which the blood is dropped and the size of the blood spatter
droplets? Support your answer with data.
2.) Blood is dropped at 15 cm and 165 cm with a 00 angle. Compare and contrast the outer edges of blood droplets
produced from these two heights.
3.) Examine your results. Is there a relationship between the height from which the blood is dropped and the number
of satellites produced?
4.) Examine your results. Is there a relationship between the medium to which the blood is dropped on to and the
number of satellites produced?
5.) Is there a relationship between the medium to which the blood is dropped on to and the size of the blood spatter
droplets? Support your answer with data.
6.) How accurate were you in obtaining the desired angles of impact?
7.) Provide an example of how knowing the actual angle of impact could help investigators solve crimes.
8.) Based on the analyses performed in this lab, could someone determine both angle of impact and distance fallen
from a single bloodstain? Explain.
9.) Would results differ if a different liquid was used instead of fake blood? Explain.