Presentation is loading. Please wait.

Presentation is loading. Please wait.

AUTOMOBILE GLASS With Thanks To Jerry Chisum Author: Evidence and Crime Scene Reconstruction.

Similar presentations


Presentation on theme: "AUTOMOBILE GLASS With Thanks To Jerry Chisum Author: Evidence and Crime Scene Reconstruction."— Presentation transcript:

1 AUTOMOBILE GLASS With Thanks To Jerry Chisum Author: Evidence and Crime Scene Reconstruction

2 SHOOTING CAR WINDOWS n American automobiles have two types of window glass. The windshield is laminated.

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

4 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

5 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.

6 n All breaks radiate from one point. n Primary lines lead to impact point. POINT OF IMPACT Stressed Glass

7 * First shot causes lines to radiate out and fracture the glass into many small pieces. SEQUENCE OF SHOTS Stressed Glass

8 * 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 SHOTS Stressed Glass

9 O The first shot sends out radial lines n 2nd shot lines may over extend 1st n The shock wave, carried by the plastic causes 1 st lines to grow. SEQUENCE OF SHOTS Laminated Glass

10 O The first shot sends out radial lines n 2nd shot lines may over extend 1st n The shock wave, carried by the plastic causes 1 st lines to grow. Like this... SEQUENCE OF SHOTS Laminated Glass

11 First Shot

12 SEQUENCE OF SHOTS LAMINATED GLASS SECOND SHOT

13 SEQUENCE OF SHOTS LAMINATED GLASS THE SHOCK WAVE EFFECT But which shot occurred first?

14 SEQUENCE OF SHOTS LAMINATED GLASS THE SHOCK WAVE EFFECT But which shot occurred first? Beats me! ?

15 SEQUENCE OF SHOTS LAMINATED GLASS THE SHOCK WAVE EFFECT With LAMINATED GLASS You Just Cant Tell! Beats me! ?

16 ONE SIDED BREAK n LAMINATED ONLY n A star shaped break on only one of the glass panes may be made by striking the opposite side. n Tap a dowel with a hammer, the opposite side breaks.

17 GLASS - VIDEO CLIPS Density Testing Density Testing + CA Hackle Marks Press Alt–Enter to view video in Full Screen Mode Press Alt–Tab to return to this slide.

18 GLASS - Hackle Marks Lets 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. Lets 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.

19 GLASS - Hackle Marks hypothesis: If the impact occurred to the glass surface on the outside of the house, then …

20 GLASS - Hackle Marks 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. OUT IN

21 GLASS - Hackle Marks 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. IN OUT Rib Marks

22 GLASS - Hackle Marks 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. OUT IN Rib Marks Inside Outside

23 GLASS - Hackle Marks 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. OUT IN Rib Marks Hackle Marks Inside Outside

24 GLASS - Hackle Marks 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. OUT IN Rib Marks Hackle Marks Inside 90º Outside


Download ppt "AUTOMOBILE GLASS With Thanks To Jerry Chisum Author: Evidence and Crime Scene Reconstruction."

Similar presentations


Ads by Google