BPA 2
- Created by: meganjayne15
- Created on: 30-04-14 12:33
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- Different blood stains
- single drop
- always spherical
- competition between two forces - surface tension and gravity
- smooth surface - smooth, spherical stain
- rough surface - jagged edges, spines present
- surface angle is important
- the smaller the angle of impact, the more elongated the drop pattern is
- elliptical - long and thin (look at image)
- wave cast off may be present (look at image)
- the smaller the angle of impact, the more elongated the drop pattern is
- secondary spatter
- blood into blood
- Impact spatter
- The drop formation of blood under impact forces
- blood follows path of least resisitance
- randomness in stain position and shows a point of convergence
- created when an individual comes into contact with an object with sufficient force to cause projection
- projectile: bullet
- sharp object: knife
- blunt object: brick
- power tool: circular saw
- classification
- mist
- fine
- medium
- large
- back spatter and forward spatter created
- usually more forward spatter than there is back spatter
- variables
- amount of wet blood
- position of impact site relative to attacker
- size and shape of weapon
- speed and angle of weapon on impact
- estimation of origin
- directionality
- dont include tail when calculating length
- where the victim was not assailant
- directionality
- Cast-off
- blood which is flung from a moving object due a change in velocity or direction
- 4 different terms used
- swing cast-off
- in line staining
- vertical or horizontal surface
- variable factors: volume of blood, length and geometry of weapon, velocity and acceleration of swing, anatomy of arm
- cessation cast-off
- down the back of the assailant
- percussive staining
- blood feathering on the weapon
- arterial damage
- due to pressure within the circulatory system forcing blood out of wound in a distinctive pattern
- pattern depends on: extent of artery damage, site of injury, direction of spurting and movement of victim
- V/W pattern
- pattern depends on: extent of artery damage, site of injury, direction of spurting and movement of victim
- 6 areas where there is an artery in the body
- temporal - forehead
- carotid - throat
- aorta - heart
- brachial - bicep
- radial - wrist
- femoral - thigh
- radial - wrist
- brachial - bicep
- aorta - heart
- carotid - throat
- temporal - forehead
- due to pressure within the circulatory system forcing blood out of wound in a distinctive pattern
- large volume stains
- caused by arterial damage or prolonged bleeding or by sudden release of large quantity of blood
- blood will diffuse into areas
- PABS
- physiological changes to blood
- diluted due to condensation, cleaning up attempts or mixing with saliva, urine, stomach fluids or cerebrospinal fluid
- blood changes colour with aging as well as mixing with other components
- red-brown-green-dark brown-black
- physiological changes to blood
- contact stains
- transfer of blood from one item to another
- wipes - wiped through blood i.e. hand print wiped through a pool of blood
- swipes - direct from item i.e. cleaning blood off a blooded weapon will create a swipe
- signatures, folds and others
- swipes - direct from item i.e. cleaning blood off a blooded weapon will create a swipe
- wipes - wiped through blood i.e. hand print wiped through a pool of blood
- transfer of blood from one item to another
- composite stains
- complex patterns
- either complex action or several patterns on target surface
- complex patterns
- single drop
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