CJE 4655 - Practical crime scene processing Chapter 12
True
Copper is deposited on scene defects as a result of friction from the impact of jacketed or semi-jacketed bullets
the solution will cause a transfer of lead acetate onto the filter paper with no evident visual change
If metallic lead is present in defect
Griess Test
Test directed at surfaces believed to be in close proximity to a muzzle when the firearm was discharged
15% solution of glacial acetic acid, using a piece of filter paper at least twice the size of the evident defect, the csi moistens the paper with acetic acid and pressed against the defect
The csi requires three working solutions for chemical tests
The ellipse matching method in bullet defects will increase the
accuracy of defining the impact angle
Griess Test
additional chemical test on scene for consideration otherwise known as Nitrate compound test
forensic firearms examiners
are the people who deal with internal ballistics. This includes the study and examination of the firearm itself, which includes ejection patterns, gunshot residue deposition, and other related aspects. Rarely have to visit crime scene
bullet defects
bullet wounds
entry defects
clean hole, demonstrate bullet wipe, and inward beveled ring around the defect
cartridge
complete unit of unfirmed ammunition. Typically made up of a bullet and casing with primers and propellant contained within
external ballistics
considers the trajectory of the bullet after leaving the barrel of the weapon. The information derived is dependent upon the scene and the targets involved.
destabilized /tumbling bullets
create irregular defects that are easily recognizable at the scene
forensic pathologists
deal with terminal ballistics, this is the investigation of the effect of a bullet on a human target and includes defining the path of the bullet through the victim
true
deformations of bullets may be able to offer information regarding the general angle at which the bullet struck the surface
trajectory rods
effective method of documenting the trajectory of a bullet given a penetrating or perforating bullet defect at the scene
True
if a bullet strikes various targets within a scene, the evidence left by those strikes can be informative. The location of these items, the shape of the resulting defect, and the interrelationship of this evidence may allow for a level of understanding
previous scarlet to turning blue-violet
if available the final confirmatory test can be accomplished by spraying filter paper with 5% solution with hydrochloric acid and will result in
the filter paper treated with sodium rhodizonate will turn bright scarlet red
in presence of metallic lead
Ballistics is broken down into three different areas of study
internal or interior ballistics, external or exterior ballistics, terminal ballistics
true
it is possible to establish a general angle of impact into the surface
chamber
location of the firearm that holds the cartridge when it is fired
"wake effect"
metal impacts - small fracture lines in the paint and on the metal itself, arching outward that indicate the direction of travel. not always evident on visual inspection
muzzle effluent consist of
nitrite compound, soot, smoke, particles of burned and partially burned gunpowder
Ejection port
opening on the side or bottom of semi-automatic or automatic weapon where the spent casings are ejected from it and live rounds are loaded into this port
CSI's
responsible for conducting external ballistics, this area considers the path and trajectory of the bullet after leaving the barrel of the weapon to its final impact. it is based on the evaluation of bullet defects in the scene
exit defects
tend to be irregular, demonstrate coning effect or demonstrate material that is pushed away from the defect
metal splash
the friction of the bullet in contact with the surface - small splashes of molten lead or copper will demonstrate evident directionality radiating away from the defect in the direction the bullet was traveling
Projectile (Bullet)
the subunit of a cartridge that is expelled from the firearm under the pressure created by the burning propellant. Bullets are typically is single mass of metal
Cartridge case
the subunit of the cartridge that holds the primer and propellant. this casing is typically made of metal and will either be expelled form automatic and semiautomatic weapons or retained in single shot or revolver type weapons.
barrel
the tubular aspect of the firearm that directs the path of the projectile when fired
true
there is an empirical relationship between the shape of the bullet defect and the angle of the bullet's impact into the target
Perforating defects
where a bullet enters a surface and exits
Penetrating defect
where the bullet enters but does not exit a surface
Tangential defects
where the bullet skims the surface creating a series of defects
Richochet or deflection
where the bullet strikes a surface and deflects off it at some angle without penetrating the surface completely