Examination of Physical Evidence

Slides:

Advertisements

Similar presentations

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

Advertisements

Physical Evidence Chapter 3: Physical Evidence

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. 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 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 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.

› 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.

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 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?

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 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.

Crime Scene Investigation and Evidence Collection.

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 Physical Evidence It would be impossible to list all the objects that could conceivably be of importance to a crime.

Warmup: Read the case study about the murder of Laci Peterson on page 82. Then answer these questions: 1.True or False: Laci Peterson was pregnant at the.

Do now: What types of things should be in a crime scene sketch?

Ku San! (greetings in Girawa) Do Now: – Take out HW Agenda: – Identification and Comparison – Wayne Williams Case HW – p103 #11-14 and p104 #1-3.

O’Connor/Chapter 3. Common types of physical evidence  Blood, semen, & saliva  Documents  Drugs  Explosives  Fibers  Fingerprints  Firearms & ammunition.

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

Forensic Science T. Trimpe 2006

2 Methods used to identify materials found at the scene of a crime.

Let the evidence speak for itself.

NOVEMBER 7, 2012 WARM-UP: STANDARD-SFS1b. Distinguish and categorize physical and trace evidence. EQ: How is physical evidence analyzed? Sit quietly, and.

Locard’s Exchange Principle “When a person comes into contact with an object or another person, a cross- transfer of physical evidence can occur.”

JS 113: Trace evidence- Hairs, Fiber and Paint I.Announcements, Assignments and Acknowledgements II.Learning Objectives (Chapter 8) a.Hair 1.Describe cuticle,

Chapter 3 Physical Evidence. Common Types of Physical Evidence Blood, semen & saliva Blood, semen & saliva Documents Documents Drugs Drugs Explosives.

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

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

1 Forensic Science Chapter 3: Physical evidence. 2 Biologicals Blood, semen, and saliva.  Liquid or dried  Human or animal  on fabrics  Cigarette.

3 Physical Evidence.

3 Physical Evidence.

Chapter 3 PHYSICAL EVIDENCE

Chapter 3 PHYSICAL EVIDENCE.

Trace Evidence – Individual vs. Class Evidence

sturgeon and striped bass

Chapter 3 Evidence.

Crime Scene Investigation

Goal: to recognize, document and collect evidence at a crime scene

“Impressive” Evidence

Created by C. Ippolito July 2007

Catalyst What pieces of evidence allowed Dupin to solve The Murders in the Rue Morgue? Objective - I will compare class and individual evidence.

Locard’s Exchange Principle

Chapter 3 Physical Evidence

Criminalistics (Saferstein)

Physical Evidence Chapter 3

Physical Evidence.

Chapter 3 Physical Evidence.

Physical Evidence Chapter 3

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.

Warm-Up List all of the evidence in the room to determine if the crime was a murder or a suicide.

Physical Evidence Common types of Physical evidence Identification of comparison of Physical evidence Individual and class characteristics Class evidence.

CHAPTER 3 PHYSICAL EVIDENCE

Chapter 3 PHYSICAL EVIDENCE.

Physical Evidence.

Chapter 3 PHYSICAL EVIDENCE. Chapter 3 PHYSICAL EVIDENCE.

Types of Evidence.

Created by C. Ippolito July 2007

Chapter 3 PHYSICAL EVIDENCE

Trace Evidence – Individual vs. Class Evidence

Chapter 3 PHYSICAL EVIDENCE.

Physical Evidence.

3-3 The Examination of Physical Evidence

Evidence Evidence can be divided into two broad types:

Presentation transcript:

Examination of Physical Evidence

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.

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.

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

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

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

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.

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

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

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.

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

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.