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