Module 10: Blood Spatter Analysis Flashcards
Blood Spatter Analysis
Analyze patterns of bloodstains
What can be inferred from blood spatter?
- direction blood origin
- angle of the blood droplet on the surface
- location/position of victim at the time bloody wound as inflicted
- movement of bleeding individual
- minimum number of blows that struck a bleeding victim
- approximate location of an individual delivering blows that produced a bloodstain pattern
Blood droplet
- spherical shape until contact on a surface
- same height, angle, surface = stains w/ same basic shape
Types of Bloodstains
- passive bloodstains
- projected bloodstains
- expiration bloodstains
- transfer/ contact bloodstains
- impact bloodstains
- gunshot spatter
- forward spatter
- back spatter
- cast-off spatter
Passive Bloodstains
- created by gravity
- pools of blood, as in tulo lang
Projected Bloodstains
- force is applied to the blood source
- injury to a main artery/ heart
True or False
Each large spurted stains does not correspond to a heart pump.
False
Expiration bloodstains
- expelled from mouth or nose coz’ of internal injury
Transfer or contact bloodstains
- bloody object/body comes in contact with a surface
What is the most common bloodstain pattern?
Impact bloodstains
Gunshot spatter
- characterized by both forward spatter (exit wound) and back spatter (entrance wound)
Forward spatter
- projected outward
- away from the source
Back spatter
- backward from the source
- talsik pabalik sa nanakit
- potentially deposited on the object or person who created the impact
Some blood enters the gun muzzle due to back spatter
Drawback effect; indicates close-range firing
Area of convergence
- location on a 2d plane from which the drops originated
- convergence of straight lines following the tails of ind. bloodstains.
Area of origin
- area in 3d plane from which blood was projected
- position of the victim when the event happen
- closer to the surface -> clustered impact pattern
True or False
Farther impact from the surface -> farther distribution and distance between drops.
True
Cast-off spatter
- caused by swingin of blood-covered object
-> fling of blood - may show minimum number of blows
True or False
The width of the cast-off pattern may help suggest the object that produced it.
True
True or False
Cast-off pattern is not enough to suggest the direction of blow
False
Factors affecting the shape of the droplet
- volume
- texture of the target surface
- angle of impact
- velocity
- height
True or False
Bigger droplets, bigger bloodstains
True
True or False
Harder and nonporous surface, more spatter
False. Less spatter
What do you call the smaller bloodstain from the parent stain?
Satellite stain
Shape of bloodstains found on rough surfaces.
Irregular shape with serrated edges, satellite stains
True or False
Exact velocity can be determined.
False
Velocity of the droplet
- higher velocity of the force of impact on the source, higher velocity of the blood droplets
- force and velocity increases, diameter decreases
True or False
Higher distance = larger diameter
True
What is the maximum diameter?
7ft
Challenges and Limitations
- contamination of crime scene can distort bloodstain patterns
- environmental factors (airflow or temp)
- interpretation varies
