# Blood Spatter Patterns Murder or Self Defense? - PowerPoint PPT Presentation

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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.

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Blood Spatter Patterns Murder or Self Defense?

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## Blood Spatter PatternsMurder or Self Defense?

Chris Schaefer, OMS II

PriyaNileshwar, OMS I

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

Good!

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 angle1 = 90 degree angle

### 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?