1. 4
Circumstantial Evidence

2. Introduction
Direct evidence involves eyewitnesses who have through one or more of their five senses, experienced something relative to the crime in question.
Circumstantial evidence is evidence from which an inference can be drawn and which includes items such as physical evidence.

3. Class and Individual Evidence
Two broad categories of physical evidence
Class evidence
Cannot be linked to a particular person or an object but only to a class of objects
May acquire individual characteristics over time
Individual evidence
Can be linked to a person or a specific object

4. Weapons Ballistics Interior ballistics Exterior ballistics
The identification of firearms, bullets, cartridges, and shotgun shells
Interior ballistics
Refers to the functioning of firearms through the firing cycle
Exterior ballistics
The study of projectiles in flight
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5. Weapons Primary sources for weapon identification The inside barrel
The firing pin
The breech face in which the firing pin is located
The chamber
The ejector
The extractor
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6. Weapons Describe the firearm by: Collect Manufacturer Serial number
Caliber
Collect
Cartridge cases
Spent bullets
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7. Weapons Gunshot residue examination
May indicate if a person has recently fired a weapon through skin analysis

8. Blood Hydrodynamics of blood drops
Indicates the distance of the fall
Indicates the direction of movement
May help to narrow the size of the suspect group
Support the identity of the suspect when located.
Plot the movements of the victim and suspect.
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9. Blood Kastle-Meyer color test determines if the stain is blood.
Luminol tests for blood that has been cleaned up by reacting with trace residue of blood and producing a blue glow in a darkened area.
Can detect bloodstains diluted up to 100,000 times
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10. Blood Precipitin tests determine if the blood is human or animal.
Gel diffusion also tests if the blood is human or animal.

11. Imprints and Impressions
Marks left on the surface by protruding parts of a person or vehicle
May include a bloody handprint, or tire tread marks
Impressions
Made by a person or object in material softer than the item of evidence
May include tire tracks or footprints
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12. Imprints and Impressions
Fingerprints may be found as either imprints or impressions.
Contaminated prints are bloody prints left on weapons or left at the scene.
Plastic prints are prints left in soft material.

13. Latent Prints
Usually cannot be seen with the naked eye and must be developed
Smooth, nonporous surfaces may be dusted with powder.
Porous surfaces, like paper, use iodine fuming or ninhydrin process.
Smooth, slippery surfaces use cyanoacrylate fuming process.

14. Fingerprints
55 million sets of fingerprints are maintained on the FBI database known as Automated Fingerprint Identification System (AFIS).

15. Tool Marks
Likely to be found at the scene of burglaries of other crimes involving a forced entry
It is important to locate the impression at the scene and to record the general description and measurements.
Photographs and measurements of the tool marks become evidence.

16. Trace Evidence: Hair
Hair can be transferred between individuals and objects during a crime.
It is typically transferred during the commission of personal crimes.
If the root bulb is attached, DNA analysis can be performed.
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17. Trace Evidence: Hair
Without DNA analysis, the crime laboratory would conduct a microscopic analysis of the hair to determine:
Origin
Racial origin
Age and sex
Forcible removal
Hair comparison

18. Trace Evidence: Fibers
Fibers are key items of evidence in personal crimes such as homicides, physical assaults, and sexual assaults where cross-transfer of fibers may occur between the clothing of the suspect and the victim.
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19. Trace Evidence: Fibers
Laboratory analysis includes the following:
Torn clothing
Microscopic examination
Analytical techniques
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20. Trace Evidence: Glass
Glass is important in hit-and-run investigations, burglaries, and assault cases when the victim is struck with an instrument such as glass bottle.
Radial fractures
Concentric fractures
Fracture match
Links the suspect to the crime as only one piece of glass will fill the void

21. Trace Evidence: Paint
Paint is usually found in the form of smears or chips.
Lacquer, enamel, and varnish can be identified by physical and chemical properties.
With automobile paints, it is possible to determine the type of vehicle.

22. Trace Evidence: Questioned Documents
Questioned documents may include checks, suicide notes, and charred papers.
The general style of a typewritten document, margins, separation of words, spelling errors, and paragraphing contribute to the identification of the person who typed it.
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23. Trace Evidence: Questioned Documents
Indented or embossed writing is sometimes found on telephone pads, and other impressionable surfaces.