Basic Bloodstain Pattern Analysis Flashcards
What can bloodstain patterns tell us?
-Position of the victim and the offender/objects at time of bloodshed
-Movement of persons/objects around a crime scene
-Fight/struggle?
-Possible type of weapon used
-Minimum # of blows, shots, actions
-Possible offender injuries (drip trail pattern exiting the scene)
-Amount of nature of blood staining on assailant
-Attempted clean up?
Bloodstain Pattern Definition…
A pattern of dried blood on a surface resulting from an event which caused blood to exit the body
Types of Bloodstains…
- Passive Stains
- Transfer Stains
- Projected/Impact Spatter Stains
- Miscellaneous Patterns
Passive Stains
Include drops, flows, and pools typically resulting from gravity acting on an injured body
Examples:
-Passive Drips
-Saturation (stabbed)
-Pool (bleeding out in a pool around the body)
-Flow Patterns (made by drops/large amounts of blood flowing by the pull of gravity)
Transfer Stains
When something wet with blood comes in contact with something that’s not or vice versa.
Examples:
-Wipe Patterns
-Swipe Patterns
-Transfer/Contact Patterns
Projected/Impact Spatter Stains
When an object comes in contact with a wet bloody source and the impact causes blood to spatter OUT
Examples:
-Splashes (blood dripping into blood)
-Cast-off patterns
-Arterial Spurt
-Gush Patterns
Miscellaneous Patterns
-VERY BROAD; CAN BE ANYTHING
Examples:
-Void Patterns
-Skeletonized Bloodstains
-Expirated Bloodstains
-Fly Spot Patterns
What are Falling Droplets?
Produce a blood pool if the source is stationary or blood “trails” if the source is moving
What is a drop tail pattern?
A series of drops that are separate from other patterns formed by blood dripping off an object/injury
What is a Saturation Stain?
An accumulation of a volume of blood without specific shape that has absorbed INTO a surface rather than on top
Examples: (carpets, bedding, clothing, wood flooring)
What are the 3 categories of Impact Spatter?
- Low Velocity Spatter
- Medium Velocity Spatter
- High Velocity Spatter
Cast-off-pattern
Is CREATED when a blood-covered object flings blood in an arc onto a nearby surface
Arterial Spray Spatter
Is CAUSED by an injury to the heart or a main artery and the pressure of the continuing pumping
Expirated Blood Patterns
Is CREATED by blood that is expelled from the mouth or nose from an internal injury
Ex: someone coughing out blood from their lungs will deposit a mixture of saliva and blood (may/may not include air bubbles)
The impact angle of blood on a flat surface can be determined by measuring the degree of…
Circular distortion
