AUTOMOBILE GLASSAUTOMOBILE GLASS

With Thanks ToJerry Chisum

Author:

“Evidence and Crime Scene Reconstruction”

SHOOTING CAR WINDOWS SHOOTING CAR WINDOWS

American automobiles have two types of window glass. The windshield is laminated.

SHOOTING CAR WINDOWS SHOOTING CAR WINDOWS

American automobiles have two types of window glass. The windshield is laminated, the rest is stressed safety glass. Each acts differently upon breaking.

DID THE IMPACT COME FROM INSIDE OR OUTSIDE? DID THE IMPACT COME FROM INSIDE OR OUTSIDE?

When regular glass is impacted the resulting fracture spreads out as it moves away from the site of impact.

Note how the angles spread outward forming a cone

Side View

DID THE IMPACT COME FROM INSIDE OR OUTSIDE? DID THE IMPACT COME FROM INSIDE OR OUTSIDE?

With laminated glass the fracture spreads out normally, but only on the front side.

Laminate spreads out the energy.

All breaks radiate from one point. Primary lines lead to impact point.

POINT OF IMPACTStressed Glass

POINT OF IMPACTStressed Glass

*First shot causes lines to radiate out and fracture the glass into many small pieces.

SEQUENCE OF SHOTSStressed Glass

SEQUENCE OF SHOTSStressed Glass

*First shot causes lines to radiate out and fracture the glass into many small pieces.

*Subsequent shots only break the small pieces. Only first shot can be traced.

SEQUENCE OF SHOTSStressed Glass

SEQUENCE OF SHOTSStressed Glass

O The first shot sends out radial lines 2nd shot lines may over extend 1st The shock wave, carried by the

plastic causes 1st lines to grow.

SEQUENCE OF SHOTSLaminated Glass

SEQUENCE OF SHOTSLaminated Glass

O The first shot sends out radial lines 2nd shot lines may over extend 1st The shock wave, carried by the

plastic causes 1st lines to grow.

Like this...

SEQUENCE OF SHOTSLaminated Glass

SEQUENCE OF SHOTSLaminated Glass

SEQUENCE OF SHOTSLaminated Glass

SEQUENCE OF SHOTSLaminated Glass

First Shot

SEQUENCE OF SHOTSLAMINATED GLASS

SEQUENCE OF SHOTSLAMINATED GLASS

SECOND SHOT

SEQUENCE OF SHOTSLAMINATED GLASS

SEQUENCE OF SHOTSLAMINATED GLASS

THESHOCK WAVE

EFFECT

But which shot occurred first?

SEQUENCE OF SHOTSLAMINATED GLASS

SEQUENCE OF SHOTSLAMINATED GLASS

THESHOCK WAVE

EFFECT

But which shot occurred first?

Beats me!

?

SEQUENCE OF SHOTSLAMINATED GLASS

SEQUENCE OF SHOTSLAMINATED GLASS

THESHOCK WAVE

EFFECT

With LAMINATED GLASS You Just Can’t Tell!

Beats me!

?

ONE SIDED BREAK ONE SIDED BREAK

LAMINATED ONLY A “star shaped”

break on only one of the glass panes may be made by striking the opposite side.

Tap a dowel with a hammer, the opposite side breaks.

GLASS - VIDEO CLIPSGLASS - VIDEO CLIPS

Density Testing

Density Testing + CA

Hackle Marks

Press Alt–Enter to view video in Full Screen ModePress Alt–Tab to return to this slide.

GLASS - Hackle MarksGLASS - Hackle Marks

Let’s see if you really understand the “hackle Marks” video… you think the suspect in a case broke his own window from the OUTside of the house in order to fake a burglary.note: this is NOT the same as in the video write an “if” / “then” hypothesis showing How you can prove it using glass hackle marks.

Let’s see if you really understand the “hackle Marks” video… you think the suspect in a case broke his own window from the OUTside of the house in order to fake a burglary.note: this is NOT the same as in the video write an “if” / “then” hypothesis showing How you can prove it using glass hackle marks.

GLASS - Hackle MarksGLASS - Hackle Marks

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

then … then …

GLASS - Hackle MarksGLASS - Hackle Marks

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

then the hackle marks would be at right angles to the glass surface on the inside of the house.

then the hackle marks would be at right angles to the glass surface on the inside of the house.

OUTIN

GLASS - Hackle MarksGLASS - Hackle Marks

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

then the hackle marks would be at right angles to the glass surface on the inside of the house.

then the hackle marks would be at right angles to the glass surface on the inside of the house.

IN OUT

RibMarks

GLASS - Hackle MarksGLASS - Hackle Marks

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

then the hackle marks would be at right angles to the glass surface on the inside of the house.

then the hackle marks would be at right angles to the glass surface on the inside of the house.

OUTIN

RibMarks

Inside Outside

GLASS - Hackle MarksGLASS - Hackle Marks

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

then the hackle marks would be at right angles to the glass surface on the inside of the house.

then the hackle marks would be at right angles to the glass surface on the inside of the house.

OUTIN

RibMarksHackle

Marks

Inside Outside

GLASS - Hackle MarksGLASS - Hackle Marks

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

hypothesis:

If the impact occurred to the glass surface on the outside of the house,

then the hackle marks would be at right angles to the glass surface on the inside of the house.

then the hackle marks would be at right angles to the glass surface on the inside of the house.

OUTIN

RibMarksHackle

Marks

Inside

90º

Outside