Glass, Physical Match, Individualization

Hans Gross

Coined “Criminalistics,” founded Institute of Criminalistics

Edmund Locard

Founded first forensic lab in Lyon, “Every contact leaves a trace”

Paul Kirk

Founded first criminalistics program in the U.S.

Principle of Individuality

“No two objects in nature are identical”

Criminalistics Activities Include:

Recognition, Identification, Individualization, Reconstruction

Class Characteristics

Group Associations

Individualization

Unique and random characteristics that link an object to only one possibility

Direct Physical Match

Slotting edges together, from broken or torn items

Indirect Physical Match

Separation surface not evident, use topological features or internal features. (Cut paper, cut wood, etc)

Direction of Force

Glass cracks at opposite side of the force

Radial Fracture

Begin at a point and radiate outward, initial crack is opposite to the force

Concentric Fracture

-Perpendicular end always faces the surface on which the force originated
- only appear on plain glass not tempered

Bullets and glass

Entrance is on small side (Exit hole larger than entrance hole)

Conchoidal striations

Edge of glass

Wallner lines

Rib-shaped markings with a wave-like pattern, concave in direction from crack propagation

Hackle Mark

Line on the crack surface running parallel to the local direction of crack spreading

Radial Fractures

the direction of the force is on the opposite side as the right angles of the Wallner lines

4R Rule

Ridges on Radial Cracks are at Right Angles to the Rear

Exceptions to 4R Rule

Laminated glass, tempered glass, small windows held firmly, thermal fracture, wire reinforced glass

Float glass

One side fluoresces, used in cars

Bullet holes and fractures

Radial fractures caused by a bullet stop at pre-existing fractures

The word “criminalistics” was introduced by?

Hans Gross

The “Exchange Principle” in Criminalistics was introduced by:

Edmund Locard

While examining a bullet hole in glass, you notice that one side of the glass has a crater.  This indicates that:

The bullet entered the glass on the opposite side of the crater

These are general characteristics that define a category of items or objects, but are not  sufficient to define individuality:

Class characteristics

In glass analysis, radial fractures (select all that apply):

Initiate on the side opposite the applied force, Extend outward like the spoke of a wheel from the point at which the glass was struck

In glass analysis, _______________ lines are also called rib marks and they can aid in determining the direction of force.

Wallner