Presentation is loading. Please wait.

Presentation is loading. Please wait.

Examination of Physical Evidence

Published byGabriel Sims Modified over 6 years ago

Similar presentations

Presentation on theme: "Examination of Physical Evidence"— Presentation transcript:

1 Examination of Physical Evidence

2 Identification vs. Comparison
Identification: The process of determining a substance’s physical or chemical identity ex. heroin, gasoline, blood, hair (what species?), etc. There must be tests that give repeatable results for each item. May be one step, may be 5 or 6 steps.

3 Comparison The process of ascertaining whether two or more objects have a common origin. ex. Similarities in hair found at a crime scene to a suspect’s hair; similarity in paint chips to paint from the suspect’s car.

4 Comparison First, you have to have a list of things to compare—a series of standard properties. ex. Hair – look at the cuticle, cortex, and medulla and compare to one from a suspect

5 Comparison Second, use that list to compare—do they come from the same source? Even if they’re indistinguishable, are they definitely from the same source? NO

6 Quality & Usefulness of Physical Evidence
Class Characteristics Individual Characteristics Mathematical Probability Rarity Locard’s Principle of Exchange

7 Individual versus Class Evidence
Class Individual Definition Evidence that can only be associated with a group source and not a single source.  Evidence that can be associated with a single, common source with an extremely high degree of certainty. 

8 Individual versus Class Evidence
Class Individual Degree of certainty of common origin  Low High 

9 Individual versus Class Evidence
Class Individual Found at the Crime Scene Usually Sometimes

10 Individual versus Class Evidence
Class Individual Value Provide corroboration of events with data that are free from human error. Collective presence may lead to extreme high certainty. Individualizes suspect to a high probability.

11 Individual versus Class Evidence
Class Individual Examples Tire tracks Shoe impressions Blood type Paint layers Fibers DNA fingerprinting Teeth Fingerprints Bullets: the striation markings on bullets

12 Collective Presence May lead to an extremely high certainty that they originated from the same source. As the number of different objects link an individual to a crime increases, the probability of involvement increases dramatically.

Download ppt "Examination of Physical Evidence"

Similar presentations

Physical Evidence The examination of physical evidence by a forensic scientist is generally undertaken for the purposes of identification or comparison.

Physical Evidence The examination of physical evidence by a forensic scientist is generally undertaken for the purposes of identification or comparison.
Physical Evidence Chapter 3: Physical Evidence

Physical Evidence Chapter 3: Physical Evidence
3 - PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ 07458 CRIMINALISTICS An Introduction to Forensic Science, 9/E By Richard Saferstein.

3 - PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ CRIMINALISTICS An Introduction to Forensic Science, 9/E By Richard Saferstein.
Chapter 3 Physical Evidence.

Chapter 3 Physical Evidence.
Chapter 3: Physical Evidence. Introduction It would be impossible to list all the objects that could conceivably be of importance to a crime. Almost anything.

Chapter 3: Physical Evidence. Introduction It would be impossible to list all the objects that could conceivably be of importance to a crime. Almost anything.
3-1 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein PHYSICAL EVIDENCE.

3-1 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein PHYSICAL EVIDENCE.
3-1 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein PHYSICAL EVIDENCE.

3-1 ©2011, 2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE: An Introduction, 2 nd ed. By Richard Saferstein PHYSICAL EVIDENCE.
Chapter 3 3.1 Physical Evidence. OBJECTIVES (don’t write) Review the common types of physical evidence encountered at crime scenes, Explain the difference.

Chapter Physical Evidence. OBJECTIVES (don’t write) Review the common types of physical evidence encountered at crime scenes, Explain the difference.
Today, 9/18 1 – Short lecture (take out notes) 2 – Start project.

Today, 9/18 1 – Short lecture (take out notes) 2 – Start project.
› Established “ Locard’s Exchange Principle ”- whenever 2 people/objects come into contact, materials will be exchanged between them. › Criminals contacting.

› Established “ Locard’s Exchange Principle ”- whenever 2 people/objects come into contact, materials will be exchanged between them. › Criminals contacting.
Chapter 3 Physical Evidence. Any & all objects that:  establish a crime  link a crime to its victim  link a crime to its perpetrator Must be recognized.

Chapter 3 Physical Evidence. Any & all objects that:  establish a crime  link a crime to its victim  link a crime to its perpetrator Must be recognized.
3-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE An Introduction By Richard Saferstein PHYSICAL EVIDENCE Chapter.

3-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein PHYSICAL EVIDENCE Chapter.
3-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE An Introduction By Richard Saferstein PHYSICAL EVIDENCE Chapter.

3-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein PHYSICAL EVIDENCE Chapter.
 Page 21  1. What is physical evidence?  2. How is physical evidence different from testimonial evidence?

 Page 21  1. What is physical evidence?  2. How is physical evidence different from testimonial evidence?
Physical Evidence Chapter 3. Types of Physical Evidence Blood, semen, saliva Document Drugs Explosives Fibers Fingerprints Firearms and ammunitions Glass.

Physical Evidence Chapter 3. Types of Physical Evidence Blood, semen, saliva Document Drugs Explosives Fibers Fingerprints Firearms and ammunitions Glass.
3 - PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ 07458 CRIMINALISTICS An Introduction to Forensic Science, 9/E By Richard Saferstein.

3 - PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ CRIMINALISTICS An Introduction to Forensic Science, 9/E By Richard Saferstein.
Physical Evidence Forensic Fuel Chapter 3. Lecture Highlights  Negative Controls  Comparison and Identification  Class vs. Individual Characteristics.

Physical Evidence Forensic Fuel Chapter 3. Lecture Highlights  Negative Controls  Comparison and Identification  Class vs. Individual Characteristics.
Crime Scene Investigation and Evidence Collection.

Crime Scene Investigation and Evidence Collection.
3-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ 07458 FORENSIC SCIENCE An Introduction By Richard Saferstein PHYSICAL EVIDENCE Chapter.

3-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein PHYSICAL EVIDENCE Chapter.
3-1 PHYSICAL EVIDENCE Chapter 3. 3-2 Physical Evidence It would be impossible to list all the objects that could conceivably be of importance to a crime.

3-1 PHYSICAL EVIDENCE Chapter Physical Evidence It would be impossible to list all the objects that could conceivably be of importance to a crime.

Similar presentations

Ads by Google