1. Evidence
"Anything which is legally submitted to a competent tribunal as a means of ascertaining the truth of any alleged matter of fact under investigation before it"

2. Direct evidence
"That which (if true) proves the fact in dispute ... in the case of a witness...it is the result of personal knowledge derived through one or more of the five senses"
Indirect or circumstantial evidence
"That which (if true) tends to establish an issue in dispute by proving another fact...[it] does not conclusively establish that issue, but causes an inference or presumption of its existence"
Real or physical evidence
"May include almost any (tangible) object...that is directly linked to crime charged and may be observed by a judge and /or jury"

3. Circumstantial physical evidence
Example: Witness testimony that an accused was known to own a revolver of the same make and caliber of that used in the commission of a homicide.
Testimonial evidence
"That which is supplied through the verbal testimony of a witness (or suspect)"
Circumstantial testimonial evidence
Example: The perpetrator of a crime was observed wearing a red shirt with vertical blue stripes; the individual accused of the crime owns such a shirt.

4. Physical Evidence
Objects that can establish that a crime has been actually committed or not

5. CONTENTS… DEFINATION - Physical Evidence… COMMON TYPE… IDENTIFICATION…
INDIVIDUAL CHARACTERISTICS…
CLASS CHARACTERISTICS…
CLASS v/s INDIVIDUAL…

6. Definition of Physical Evidence
“Physical evidence comprises all objects that can establish that a crime has been committed or can provide a link between a crime, suspect & victim and its perpetrator.”

7. Common Types of Physical Evidence
Blood, Semen, and Saliva –these are subject to serological and biochemical analysis
Documents – any handwriting, typewriting, ink, indented writing, obliterations, burned or charred documents
Drugs
Explosives – any device with an explosive charge and any item that may contain the explosive residue
Fibers – any fiber that may show cross-transfer between object and/or persons
Fingerprints – latent and visible

8. Common Types Continue…
Firearms and Ammunition
Glass – particles that may show cross-transfer or panes that may have bullet holes
Hair – animal or human hair showing cross-transfer
Impressions – tire markings, shoe prints, depressions in soil, glove or fabric impressions, bite marks in skin or food
Organs and Physiological Fluids – body organs and fluids are tested for drugs and poisons
Paint – particles showing cross-transfer (auto accidents)

9. Common Types Continue…
Petroleum Products – gas residues from arson scenes, grease or oil stains
Plastic bags – usually for drug residues
Plastic, Rubber or other Polymers- cross-transfer
Powder Residues – firearm discharge residues
Serial Numbers – stolen property submitted to lab for serial number restoration
Soil and Minerals – cross-transfer (esp. soil embedded in shoes)

10. Common Types Continue…
Tool Marks – any object suspected of having an impression of another tool in it (ex. – crowbar may leave marks on a windowsill in a break-in)
Vehicle Lights – examination of vehicle lights can determine whether they were on or off at the time of impact
Wood or other Vegetative Matter – cross-transfer

11. Identification of a Substance
Identification – process of determining a substance’s physical or chemical identity

12. Identification Continue…
Drug analysis, species determination.
Common standard tests are used to determine identity. There are standard tests for most drugs, blood species of origin and explosive materials or any type of specific physical evidence.
Some materials can be determined with one test while others may require several tests.

13. Comparison
Comparison--process of determining whether two or more objects have a common origin

14. Comparison Continue…
Scientists will compare the control and suspect specimen to determine if they are the same
This type of analysis can assist in placing a suspect at the scene
Two-step Procedure:
combos of select properties of the control and suspect specimens are chosen for comparison
once the examination is completed, the forensic scientist will render a conclusion as to how closely related the two specimens are

15. Comparison Continue…
If any of the selected properties are not alike, the scientist will declare that the two items are not from the same source. However, if all of the selected properties match, they still may not be able to conclude that the two specimens are from the same source with 100% accuracy.
Therefore, usually only the probability that two specimens came from the same source is given

16. Individual Characteristics
Individual Characteristics – Properties of evidence that can be attributed to a common source with an extremely high degree of certainty

17. Individual Characteristics Continue…
Examples: DNA, fingerprint ridges, grooves/striations on a bullet or toolmark, irregular and random wear patterns on tire or shoe impressions, handwriting characteristics, fitting together pieces of broken objects, matching the striations in sequentially made plastic bags, etc.
The probability of two people having the same fingerprints is 1 x (1 followed by 60 zeros).

18. Class Characteristics
Class Characteristics – Properties of evidence that can only be associated with a group and never with a single source

19. Class Characteristics Continue…
Examples: new factory painted cars with only two-layers of paint, blood to a certain degree
Uses of Class Characteristics are usually to corroborate the events with data that are free of human bias

20. Individual v/s Class Characteristics
The more objects that can place a suspect at the scene, the higher the probability that the person was there, even if only class characteristics are present.
Individual and Class Characteristics can often exonerate a person as well.

21. THANK YOU………………..