BPA 2

HideShow resource information
View mindmap
  • 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)
      • 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
    • 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
      • 6 areas where there is an artery in the body
        • temporal - forehead
          • carotid - throat
            • aorta - heart
              • brachial - bicep
                • radial - wrist
                  • femoral - thigh
    • 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
    • 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
    • composite stains
      • complex patterns
        • either complex action or several patterns on target surface

Comments

No comments have yet been made

Similar Other resources:

See all Other resources »See all Forensic Investigation resources »