1. Forensic Soil Analysis

2. Forensic Definition of Soil
Any disintegrated surface material, natural or artificial that lies on or near the Earth’s surface.
Natural= rocks, minerals, vegetation, animal matter
Manufactured= glass, paint, asphalt, brick fragments, cinders

3. Soil
The value of soil as evidence rests with its prevalence at crime scenes and its transferability between the scene and the criminal.
Most soils can be differentiated by their appearance and color.
The first step in exam-
ination of soil is a side-by-
side examination of color
and texture.

5. Soil Types-Texture
People describe soil types in all kinds of ways such as heavy, light, sandy, clay, loam, poor or good.
Soil scientists describe soil types by how much
sand, silt and clay are present. This is called texture.

7. What is the first step in the examination of soil?
Side-by-side comparison of color and texture

8. Comparison Microscope
Soil appears different when wet, therefore samples are dried in the same manner in the lab
1,100 distinguishable soil colors
Low power magnification offers presence of plant and animal debris
High magnification can classify minerals and rocks

9. Mineral Naturally occurring crystalline solid
UNIQUE
COLOR
GEOMETRIC SHAPE
DENSITY
REFRACTIVE INDEX
2200 exist, but only 20 are common and found readily at the surface surface

10. Rocks Made of a combination of minerals
Characterized by their mineral content and grain size

11. Mineral Analysis
Rocks and minerals are used to manufacture a wide variety of industrial and commercial products; safe insulation, brick, plaster and concrete blocks for example.

12. Which magnification allows you to see naturally occuring crystalline solids?
High Magnification

13. Density Gradient Tubes
These tubes are typically filled with layers of liquids that have different density values.
When soil is added to the density-gradient tube, its particles will sink to the portion of the tube that has a density of equal value.

14. What is the main issue with the use of Density Gradient tubes?
Many soils from different areas yield similar densities
What is the main issue with the use of Density Gradient tubes?

15. Variations in Soil Crime Scene
Ultimate value depends on its variation at the crime scene
If the soil is indistinguishable for miles surrounding the crime scene, it will have limited value in associating soil found on the suspect with that particular site.
Variations in soil composition must be made every yards from the crime site.

16. Collection of Soil
Standard/reference soils are to be collected at various intervals within a 100-yard radius of the crime scene, as well as the site of the crime, for comparison to the questioned soil.
Soil found on the suspect, such as adhering to a shoe or garments, must not be removed.
Instead, each object should be individually wrapped in paper, and transmitted to the laboratory.

17. Collection
Soil must be collected at all alibi locations that the suspect claims
For Standard/ Reference samples: In most cases, only a tablespoon or two of the top layer of soil is collected, placed in individual plastic containers, and labeled according to location.

18. Where are all the locations soil should be collected?
Crime scene, 100 yds radius of crime scene, alibi locations, any object or clothing of interest that contains soil