Ch 10 Blood Spatter Labs. pt

Blood Spatter
By: By:
Jen Jendraszek
Jen Jendraszek
Jackie Heider
Jackie Heider
Depending on the distance and
direction that blood is dropped from a
surface, the shape and size of the
droplet will be affected.
The shorter distance the drop is from the
surface, the smaller and smoother the
droplet will be.
above the
› Notice how the
droplets are smooth
and have a 1cm
› AVERAGE: 1.1cm.
FROM 30 cm
above the
› Due to the
increase in
distance from the
surface the blood
spatter has grown
larger and shows
signs of scalloping.
› AVERAGE: 1.43
› The distortion around the edges of the
FROM 50 cm
above the
› The splatter is
noticeably larger
with a wider spread
of scalloping and
secondary spatter.
› Average: 1.58 cm.
The point of convergence is the central
point of the spatter and indicates the
location of the removed object.
With the point of convergence
determined you are then able to tell the
origin of the blood spatter.
By drawing lines
through the long
axis of the various
eliptical blood
drops you are
able to see where
the object had
been or the
spatter had
When blood is hits a surface at an angle
the spatter elongates, creating an oval
(or eliptical) shape. At the end of the
oval shape a tail may appear following
the flow of the “cast off” (the tail always
points in the direction of travel).
By measuring the width
and length of a blood
droplet you are able to
calculate the angle of
Length: .5cm
Width: 1.0cm
0.5/1.0 = 0.5cm
With that information we
are then able to
determine the angle of
trajectory by comparing
the measurement in the
Appendix A: Sine Table;
giving us an angle of 30
In order to find the angle of impact of a
blood drop divide the width by the
 You then take that measurement and
locate it in the Appendix A: Sin Table.
We alternated the angles of the paper
from first 30 degrease and then to 45
degrease and finally to 60 degrease.
 For each alteration we dropped blood
onto a plane sheet and allowed it to dry.
 Once the blood spatter dried we then
took measurements, comparing the
results to the Appendix A: Sin Table.
 From this observation we were able to
determine the angle of impact.
Because our
droplets were too
large we were
unable to
determine the
proper angle of
trajectory; however
the proper
should have
amounted to 60
Though we angled the paper at 60
degrees, the proper angle of trajectory is 30
degrees because the angle of the surface
added to the angle of trajectory must
amount to 90 degrease
 (30 + 60 = 90 degrease.)
› 30 degrease was the angle of the paper.
› 60 degrease was the measurement the
calculations should have amounted to in the
Appendix A: Sin Table.
› We know this because 30 + 60 = 90, and 90
degrease is the angle a flat surface.
Our measurements
amounted to:
› Width: 1.2
› Length: 1.7
› 1.2/1.7= 0.7
› 0.7 reads out to be
45 degrees.
Our measurements
amounted to be:
› Width:1
› Length:2
› ½= 0.5
› 0.5 reads out to be
30 degrees.
Blood spatter (bloodstains) can be used
to help piece together events that
resulted in bleeding; the information
blood spatter provides can aid an
investigator in his search to determine if
a crime was committed or not (and if so
if the blood can be considered as
evidence in the crime at hand).

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