Transcript Blood Spatter Patterns Murder or Self Defense?

Blood Spatter Patterns
Murder or Self Defense?
CHRIS SCHAEFER, OMS II
PRIYA NILESHWAR, OMS I
NNAEMEKA DIRIBE, OMSI
Types of
Patterns
High
Velocity
Medium
Velocity
Low
Velocity
How can we find out
where the blood
came from?
Pattern Analysis
Select drops of blood with an
easily identifiable shape
Measure length and width of
droplet
Pattern Analysis
Divide width by length
This gives you the sine of the
angle at which the blood
impacted the wall
Pattern Analysis
 Measure angle with protractor and
attach a string next to the droplet at
angle of impact
 Where all the strings come together
gives location of source of blood
Which Drops are Good?
Good!
Which Drops are Good?
Bad!
Measure Length and Width
Divide Length by Width
Width
Length
Determining Angle
This will give you a decimal
number
The actual formula (for those of you
with a little bit of Trigonometry) is
arcsin(number)=angle
Math?!? Say
What?
Determining Angle
 We can just estimate with this table
 .1 = 6 degree angle
.2 = 11 degree angle
.3 = 17 degree angle
.4 = 24 degree angle
.5 = 30 degree angle
.6 = 37 degree angle
.7 = 45 degree angle
.8 = 53 degree angle
.9 = 64 degree angle
1 = 90 degree angle
Measure Angle and String
Area of Convergence
Case
How can we know if a
killing was due to self
defense or murder?
Story
Stewie states that he was defending himself
against Brian who was coming after him with a
knife. Both of them were standing when this
happened. Stewie says he struck Brian in the
head while he was still standing.
Evidence
Is he telling the
truth?
High or Low Velocity ?
Good or Bad Pattern?
Good
Pattern
must have a
tail.
True/False?