1. Chapter 15- Soil and Glass Analysis and Paint too!

2. What is Soil?

3. Soil Material Partly Organic Partly Inorganic Decaying matter
Ex. Peat: 100% Organic
Partly Inorganic
Minerals
Ex. Sand: 100% Inorganic

4. What’s in soil? Rocks Minerals Vegetation Animal Waste Glass
Construction Debris
Asphalt

5. How Do Soils Differ?

6. How Do Soils Differ? Color Texture Particle size pH Density
1,000 different colors
Wet soils appear dark!
Texture
Particle size pH
Density
Fossil types (Diatoms)
Mineral and Rock Content
Pesticides/Herbicides?

7. Forensic Geology:Geo-Tracking

8. Forensic Geology: Geo-- Tracking

9. Forensic Geology: Geo-Tracking

10. Minerals and Rocks?

11. Minerals =Naturally occurring crystals (2,200 known)
Look at: Color, shape, density, refractive index

12. Minerals
Fluorescence

13. Rocks
= Contain a combination of different minerals

14. Soil and Crime
Hit and Run: - Under-fender dirt/soil deposited at impact with the victim. matching the grease on the victim with the grease under the car.
Rape: - Soil on clothing of a suspected rapist placed suspect at the crime scene.
Murder: - Soil found on murder victims used to determine the location of homicides, especially when the murder occurs in one location and the body is then moved.
Assault: - Identifying the type of rocks used as weapons led to the source of the rocks and helped locate suspects.

15. Soil Evidence Collection
Keep soil in clumps if from car
Layers tell the history of the soil being added to the car

16. Soil Evidence Collection
Collect soil at crime epicenter and at intervals up to a 100 yard radius from crime
100 yds
1 or 2 tablespoons of TOP SOIL
All soils packaged separately

17. Glass
One of the oldest manufactured product
Amorphous

18. Ingredients to make glass:
Sand (mostly silica sand)
Soda (Na2CO3)-lowers melting point
Lime (CaO)-makes it water insoluble
Combination of metal oxides:
Ex. Sodium, calcium, magnesium, aluminum
between 1,500 and 2,500 degrees Celsius

19. Glass Production Video

20. Tempered or Safety Glass
Car glass
Dicing and little splintering
Stress glass by rapid heating and cooling
=annealing
Glass also strong from lamination
Thin piece of plastic between glass layers

21. Borosilicate glass Able to withstand high temperatures 1500 F
Add boron oxides to mix

22. Bullet-Proof Glass

23. Glass Fracture Analysis

24. Glass Fractures Crime Scene Reconstruction:
-Force and Direction of Impact
-Type of projectile (bullet or rock)
Concentric Fractures
Radial Fractures

25. Projectiles+Direction of Force
Exit side of bullet is a deep crater
3R Rule
=Radial cracks form a Right angle on the Reverse side of force
Concentric fractures originate on the force side of glass

26. Multiple Bullet Holes A B
Which Bullet Came First?

27. Bullet Holes
Radial fractures caused by the passage of a bullet will stop at any pre-existing fracture

28. Mechanical Fit Analysis
Physical Fit of Edges
Look at Glass Ream Patterns

29. Glass as Forensic Evidence
Glass fragments recovered from clothing
number & distribution are important
a piece of glass embedded in a shoe has low probative value
many small fragments from a shirt or sweater can be highly significant
Glass must be classified
window glass vs broken bottle glass
Individualization may be possible

30. Other Classification Methods
Microscopy
float glass is absolutely flat
wine glasses are slightly curved
bottles have microscopic defects from mold
Fluorescence
when excited by UV radiation, many glasses exhibit fluorescence
caused by heavy metals (including tin)

31. Fluorescence
Can differentiate between float and non-float window glass
Can differentiate between different samples of float glass in some cases
(a) non-float glass or non-float side
(b) float side Sample #1
(c) float side Sample #2

32. Comparative Studies If R.I.=1.5290 then found in 1/2000 specimens
FBI has a data base of from glass manufacturers of densities and refractive indexes
=Used for frequency of occurrence issues
If R.I.= then found in 1/2000 specimens
If R.I.= then found in 22/2000 specimens

33. Problem!
Most glass is uniform in its making and show no individualistic traits!

34. Refractive Index

35. Trace Chemical Analysis of Glass

36. Properties of glass and soil
Physical Properties; can be measured without changing the substance, i.e., color, hardness, Refractive Index, birefringence, density, melting point, etc...
Chemical Properties; the way a substance changes (reacts), i.e., combustion

37. Density Determination
D = m/V
Sink or float
Density Gradient Tubes
Volume Displacement Method

38. Refraction
The bending that occurs when a light wave passes at an angle from one medium to another (air to glass)
bending occurs because the velocity of the wave decreases

39. Refractive Index Determination
Becke Line=Bright Halo that disappears when medium and fragment have the same refractive indexes
Medium index can be varied by adjusting temperature of stage

40. Birefringence (a.k.a.Double Refraction)
Refraction of light in 2 directions
Sandwich between polarizing filters

41. Paint
Where do we find painted surfaces?

42. Paint and Locard’s Principle
Small pieces of paint are often unwittingly transferred between objects during
vehicle accidents,
burglaries,
robberies,
assaults,
homicides,
even from simple contact with freshly painted surfaces during a crime.

43. Paint Composition
Paints are opaque coatings that are typically made up of three components:
Pigment: very tiny particles of organic and inorganic colored compounds that give the paint its characteristic hue.
Binder: suspends the pigment particles and helps to firmly fix them to the surface.
Solvent: such as water or an organic liquid, provides a consistency suitable for spreading the paint on the surface.

44. Paints vs. Dyes
Dyes:
usually a soluble compound that binds directly to the material and does not require any medium to bind the colored material to the surface.

45. Proper collection and preservation of paint evidence from an automobile suspected of being involved in hit-and-run incident. Paint that is foreign to the suspect automobile is observed.

46. Procedure
Scrape the foreign paint as well as all underlying layers of paint off the car’s surface using a clean knife or scalpel. The scraping must clearly show the layer structure of the paint.
Obtain a control paint sample from an adjacent undamaged area of the car. Again, all layers must be included.
Package each paint specimen separately in a proper container. A druggist fold or a vial makes an excellent container.
Label all specimen containers. Evidence collector’s name or initials, the date, and the sampling location are to be shown. All items collected are to be described in the evidence collector’s field notes.

47. Paint As Evidence
Individual Characteristics or Class Characteristics?

48. Class unless……
Multilayered Paint Chip
Custom Finishes

49. Problem A single type of car paint can be on many different models
For a given color/type of paint, batches don’t vary much in composition
Binder chemical composition may vary very slightly from batch to batch
What to do? What to do?

50. PDQ (Paint Data Query)
Law enforcement database of specific paint formulas added onto cars since 1974

51. Pigments and History
● Ochre is a mineral that has been sought and used by humans even before homo sapiens came into existence
● It has been used as:
Body paint
Artist paint
Sun blocker
Medicine (antiseptic and clotting agent)
Possible religious symbol for blood, life, etc

52. Prehistoric Cave Paintings
Pigments
~35, ,000 ybp
Homo Sapiens
Prehistoric Cave Paintings
Pigments Used
Charcoal, lampblack (soot) C
Pyrolucite, MnO
Hematite, Fe2O3
Magnetite, Fe3O4
Limonite, Fe2O3 *H2O
There is good evidence that in the cave paintings that many of the colors were a mixture of various pigments, and at some sites there is evidence that ochre was calcined (heated) to get other colors

53. Pigments Prehistoric Cave Paintings

54. Mineral Pigments in Use from Ancient thru Medieval Times
Hematite Magnetite
Limonite Goethite
Malachite Azurite
Cinnabar Chrysocola
Lapis Lazuli Realgar
Orpiment Cinnabar
Verdigris (copper acetate - Ancient Greek)
Van Dyke Brown (17th century peat extract)

55. Hans Van Meegeren
Traded fake paintings for genuine artwork in the 1930s

56. Christ and the Disciples at Emmaus
Supposedly an undiscovered masterpiece by Vermeer

57. Johannes Vermeer
Last Supper supposedly by Vermeer

58. Technique
Used a synthetic phenolformaldehyde resin - known as Albertol or Ambertol - dissolved in a spirit such as turpentine and/or an essential (i.e., non-fatty) oil such as oil of lilac or oil of lavender, which would then be mixed with hand-ground powder pigments.

59. He heated the resin transforming its chemical composition so that chemical tests would show it is really not the chemical it actually was
He painted over low value17th century paintings. He scraped away old painting

60. “Leveling Paint”

61. Art Fraud analysis
Art Forger

62. Pigments in Forensic Geology
● Because many of the pigments are minerals standard geological techniques such as microscopy, X-ray diffraction, SEM analysis, and optical spectroscopy can be used to discriminate them
The organic vehicle or binders can be discriminated by Gas Chromatography – Mass Spectrometry