Topic 5 - Shooting Scene Investigation Flashcards
What is shooting reconstruction?
Physical evidence, various theories
“is the process of utilising information derived from physical evidence at the scene, analyses of physical evidence, and inferences drawn from such analyses to test various theories of the occurrence of prior events”
What is shooting re-enactment?
Demonstration, conjecture
.“is but a demonstration of a previously existing reconstruction based on conjecture rather than scientific principle”
What are the 4 main outcomes when a bullet impacts a surface?
Intact, fragments
- The bullet remains intact and passes through causing identifiable entry and exit holes.
- The bullet remains intact but does not pass through; there is an entry but no exit hole.
- The bullet does not remain intact and some, or all of the fragments are either retained or pass through.
- The bullet bounces off either intact or fragmented.
What are possible indicators for the use of firearms?
Fragments, HEP
- Bullet, cartridge or fragments
- GSR deposits, but only at close range and subject to confirmation tests.
- Size and shape of the hole in a wall or other object.
- Evidence of high energy penetration and damage highly local to the hole, which depends on the material.
How do metals look when they’ve been shot through? (Wipe ring)
- Normally quite easy to distinguish and
usually neat on the entry side of the hole. - Exit side will look like a ‘truncated’ funnel.
- There may be a wipe ring on the inside of the funnel.
- Will just be a dent if the plate is thick.
- Paint or surface mark if the plate is very thick.
In metals, what does the length of the funnel depend upon?
Construction
- Caliber & Projectile velocity.
- Physical characteristics of the metal.
- Bullet construction.
What does wood and frangible materials look like when they’ve been shot?
Wipe ring, delaminate
- Neat on the entry side of the hole.
- Cratered and splintered on the exit side, with widely distributed debris on the exit side.
- Low velocity, large calibre will cause significant splintering on the exit side.
- Small calibre, high velocity makes a neater hole.
- Softwood tends to splinter less than hardwood.
- Plywood will delaminate with large sections of the back layer being torn away.
- There may be a wipe ring towards the entry side.
What does glass look like when they’ve been shot?
propogate
- High-velocity bullets tend to leave small neat holes with little fracturing.
- Low velocities are the opposite.
- You can also determine the Order of impact
- radiating cracks will not propagate across an
existing fault.
- radiating cracks will not propagate across an
If shot through fabric how can this be useful?
- If aligned with a wound, you can follow the bullet path into the body from the clothing.
- GSR if a close-range shot, you may get a bullet wipe ring too at all ranges.
- For synthetic fabrics: Microscopic examination at the edge of the hole will show evidence of individual fibres melting, resulting from the frictional heating caused by the bullet’s transit.
- Natural fabrics: Microscopic examination will reveal fibres with shredded and frayed ends around the hole.
What evidence can you obtain from the firearm user and object nearby?
Imprints, ricochet, debris, hearing
- Flash burns on user and target.
- Including GSR on the skin of the user and target.
- Burns to fabrics and flammable surfaces.
- Imprints and impressions.
- This might include ricochet damage.
- Bullet/fragment wounds.
- This might also include wounds from debris launched by the bullet impacting a surface.
- Hearing damage.
What is a slide bite?
Inexperienced users, recoiling, pistol grip
- This is common with inexperienced users
- This is where the recoiling slide on a SLP cuts the web between thumb and index finger on the hand holding the weapon.
- This is from holding the firearm too high on the pistol grip
What is eye relief?
- This is the optimal distance at which the view is in focus.
- This is designed to allow for recoil.
What wound is likely if an individual doesn’t know about eye relief?
This leaves a characteristic crescent-shaped contusion on the forehead or nose of the shooter.
What is a hammer bite and how is it helpful in investigations?
DNA
- SLPs with an external hammer can pinch the web between thumb and fingers.
- Different from slide bite in that a mark may be present that can be matched specifically to the hammer.
- There may also be DNA left on the firearm hammer chequering
Where are recoil marks left?
- Recoil marks left on the body will vary and are dependant upon type of weapon used and the experience of the user.
- Rifles and shotguns will imprint on the shoulder and upper arm through clothing
- Handguns may imprint chequering and grip patterns on the palm and web of the hand.
- These imprints may be short-lived indents, or
long-term bruising.
