Basic Bloodstain Pattern Analysis

Question 1

What can bloodstain patterns tell us?

Answer 1

-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?

Question 2

Bloodstain Pattern Definition…

Answer 2

A pattern of dried blood on a surface resulting from an event which caused blood to exit the body

Question 3

Types of Bloodstains…

Answer 3

1. Passive Stains
2. Transfer Stains
3. Projected/Impact Spatter Stains
4. Miscellaneous Patterns

Question 4

Passive Stains

Answer 4

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)

Question 5

Transfer Stains

Answer 5

When something wet with blood comes in contact with something that’s not or vice versa.

Examples:
-Wipe Patterns
-Swipe Patterns
-Transfer/Contact Patterns

Question 6

Projected/Impact Spatter Stains

Answer 6

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

Question 7

Miscellaneous Patterns

Answer 7

-VERY BROAD; CAN BE ANYTHING

Examples:
-Void Patterns
-Skeletonized Bloodstains
-Expirated Bloodstains
-Fly Spot Patterns

Question 8

What are Falling Droplets?

Answer 8

Produce a blood pool if the source is stationary or blood “trails” if the source is moving

Question 9

What is a drop tail pattern?

Answer 9

A series of drops that are separate from other patterns formed by blood dripping off an object/injury

Question 10

What is a Saturation Stain?

Answer 10

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)

Question 11

What are the 3 categories of Impact Spatter?

Answer 11

1. Low Velocity Spatter
2. Medium Velocity Spatter
3. High Velocity Spatter

Question 12

Cast-off-pattern

Answer 12

Is CREATED when a blood-covered object flings blood in an arc onto a nearby surface

Question 13

Arterial Spray Spatter

Answer 13

Is CAUSED by an injury to the heart or a main artery and the pressure of the continuing pumping

Question 14

Expirated Blood Patterns

Answer 14

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)

Question 15

The impact angle of blood on a flat surface can be determined by measuring the degree of…

Answer 15

Circular distortion

Question 16

What is the area of convergence?

Answer 16

The point on a two-dimensional plane from which the drops in an impact pattern originated

-will show the position of the victim/suspect in space when the stain event took place