1. NOVEMBER 15, 2013
EQ: What techniques are used in Forensic Science to analyze glass?
You DO NOT need your composition books for the warm-up today.
WARM-UP:
Today we will have a “HAIR CHALLENGE” in which you and a partner will observe several microscopic pictures of hair. You must identify the origin of each hair and write it down on the paper that will be given to you.

2. OCTBER 1, 2015 EQ: HOW IS GLASS ANALYZED TO SOLVE CRIMES?
WARM-UP: (Write the questions & answer the questions while watch the following the video.)
What are the names of the Central Park Five?
Were they innocent of committing any crimes?
Why do you think they confessed to raping the victim?
What role did the media play in how they presented the story?

3. MARCH 14, 2016 EQ: HOW IS GLASS ANALYZED TO SOLVE CRIMES?
WARM-UP: Case 004
Make as many observations about the crime scene on the next slide and be prepared to answer questions about the crime scene.

4. What do you think happened?
Crime Scene 004
Study this crime scene.
What do you think happened?

5. Crime Scene 004 What happened… Detroit, Michigan (January 2009)
Dead body in elevator shaft of abandoned building
Body is frozen in 2-3 feet of ice
Finder playing ice hockey in basement
What actually happened has not been reported

6. What do you think happened?
Crime Scene 004
Study this crime scene.
What do you think happened?

8. Forensic Analysis of Glass:

9. Glass
Hard, brittle, amorphous substance composed of sand mixed with various metal oxides
Links a suspect at the scene of a crime
*Amorphous-(atoms or molecules are arranged in random or disordered positions)

10. TEMPERED GLASS
Glass to which strength is added by introducing stress through rapid heating and cooling of the glass surfaces
When it breaks it does not shatter, but fragments or “dices” into small squares with little splintering
Ex. side and rear windows of cars

11. LAMINATED GLASS
Two sheets of ordinary glass bonded together with a plastic film
Ex. Windshields of U.S. cars

12. Which type of glass dices into pieces when it breaks?

14. Rolled Glass
Float Glass
Float Glass Process

15. DENSITY
=MASS/VOLUME
Flotation Method: standard/reference glass is immersed in bromoform and bromobenzene and bromo. is added until the glass floats
glass density=liquid density

16. Refractive Index:
When 2 substances have different RI, light passing through them produces a Becke Line

18. The Becke line disappears- medium and fragment have similar
Immersion Method glass particles are immersed in a liquid whose refractive index is adjusted until it equals that of the glass particles (match point)
A Becke line- a bright halo observed near the border of a particle immersed in a liquid (usually silicon oil) of a different refractive index
The Becke line
disappears-
medium and
fragment
have similar
refractive indices

19. Which method uses the density of a reference glass to determine the density of the unknown sample?

20. Use the following words to create 2-3 related sentences.
WORD SPLASH!!!!
Use the following words to create 2-3 related sentences.
Becke line
Flotation method
Immersion method
Density
Laminate glass
Tempered glass
Refractive index

22. Frayer Models: Laminate Glass Becke Line Tempered Glass
Flotation Method
Immersion Method
Definition
Definition in your own words
Picture
Example

23. Color, diameter, striations, pitting of fibers, cross-sectional shape
MARCH 15, 2016
EQ: HOW CAN GLASS FRACTURES BE USED TO ANALYZE A CRIME SCENE?
WARM-UP: (Write the questions & answers)
What is the name of the structure from which hair grows?
Name (2) characteristic used to identify synthetic fibers.
What type of glass is used on the rear window of cars?
follicle
Color, diameter, striations, pitting of fibers, cross-sectional shape
tempered

25. GLASS DATABASES:
Glass databases using the refractive indices (RI)

26. Populations of
Glass RIs

27. Glass bends in response to any force exterted on it’s surface

28. Direction of Penetration
A projectile hole is inevitably wider at the exit side
bsapp.com

29. Direction of Penetration
1. Radial
2. Concentric
bsapp.com

30. How does Glass break?
Forensic Fracture Analysis

31. Radial Begin at a point and radiate outward from point of impact
-initial crack is on the side
opposite the applied force

32. Concentric Motion of the projectile through the glass
puts tension on the front surface of the glass,
causing concentric fractures.
-the exit hole helps to determine the direction on impact.

33. Fractures
Concentric
Radial
bsapp.com

34. Which glass fracture occurs first upon impact?
Radial

35. Stress Marks
Radial Cracks-the perpendicular edge of stress marks is always found opposite the side where the force was applied
bsapp.com

36. Concentric Fractures: (opposite of radial)
The perpendicular end always faces the surface on which the force originated

37. Direction of Penetration
1. Radial
2. Concentric
bsapp.com

38. 3R Rule:
Radial cracks form a Right angle on the Reverse side of the force.

39. Which type of crack forms right angles on the opposite side of where the force was applied?
Radial cracks

40. Counting Bullet Holes
Determination of the sequence of bullet holes can be made by noting the radial fractures.
Radial fractures caused by the passage of a bullet stop at pre-existing fracture.

41. Successive Penetrations
A fracture always terminates at an existing line of fracture
bsapp.com

42. bsapp.com

43. bsapp.com

44. bsapp.com

46. How much glass should be collected at a crime scene?
ALL!!!

47. Submit all glass evidence found on suspect and at the crime scene
What must an evidence collector do when an individual fit of glass pieces is not possible?
Submit all glass evidence found on suspect and at the crime scene

48. Individually wrapped in paper
Suppose a suspect’s shoes/clothing has glass, how should it be packaged?
Individually wrapped in paper

49. When you are finished gluing your fractures, explain fractures using the following terms:
Radial fractures
Concentric fractures
Stress marks
Force applied
Perpendicular edge

50. Cut out the bullet hole and remaining glass pieces and swap glass pieces with someone and glue them to your paper.
Label:
Radial Fracture
Concentric Fracture

52. the hole would be smaller on the entrance side
OCTOBER 5, 2015
EQ: How is glass analysis used to solve crimes?
WARM-UP: Write and answer the following questions. When you’re done start reading the lab procedures.
Which type of crack occurs on the opposite side of the force applied?
Which type of crack occurs after the first and is circular in shape?
How can you tell which side of the glass the object hit first?
radial
concentric
the hole would be smaller on the entrance side