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Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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FORENSIC SCIENCE
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Application of science to the law
Society is dependant on rules of law
Applies knowledge and technology to
enforcement of laws
Science is used to help solve the argument
in the criminal justice system
Science is accurate and objective
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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FORENSIC SCIENCE
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The application of science to those criminal
and civil laws that are enforced by police
agencies in a criminal justice system
This course
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Chemistry, Biology, Physics, and Geology useful
for determining evidential value of crime scene
and related evidence
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
All rights Reserved
Cengage/NGL/South-Western © 2016
FORENSIC SCIENTISTS
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Aka criminalist
Can appear for either side
Can appear in criminal or civil matters
Tend to present findings in written reports
Can attend and testify in person
Give objective opinion of evidence analysis
Integral part of criminal justice system
TV shows
Juries expect forensic scientists to be experts in all
areas now because of TV shows like CSI
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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TYPICAL INVESTIGATION
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Crime scene investigators
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Gather evidence from:
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Crime scene
Suspect
Victim
Forensic Scientists
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Examine evidence
Provide scientific findings
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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PHYSICAL EVIDENCE
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Articles of materials
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Found in conjunction w/a criminal
investigation
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Assists in identifying the suspect or in
determining the circumstances under which a
crime was committed
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Sources of Physical Evidence:
Crime scene
• Science:
Suspect(s)
Forensic
Fundamentals & Investigations, 2e
Chapter 2
• Victim(s)
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Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
HOW AN ITEM BECOMES PHYSICAL
EVIDENCE
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Before an object can become evidence, it
must be recognized by the investigator as
having a relationship to the crime committed
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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EXAMPLES OF PHYSICAL
EVIDENCE
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BLOOD
HAIR
FIBERS
PAINT
GLASS
FIREARMS EVIDENCE
IMPRESSIONS
o FLAMMABLE SUBSTANCES
o ETC.
Forensic Science: Fundamentals & Investigations, 2e
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Chapter 2
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Types of Evidence
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Direct evidence
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Circumstantial evidence
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First-hand observations
Indirect evidence that can be used to imply a fact
but that does not prove it
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
Types of Evidence (continued)
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Class evidence
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Individual evidence
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Narrows an identity to a group of persons or
things
Narrows an identity to a single person or thing
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Packaging Evidence
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The paper bindle is ideal packaging for small,
dry, trace evidence.
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
SCIENTIFIC REQUIREMENTS OF
PHYSICAL EVIDENCE
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Adequate sample must be provided
Sufficient standards (knowns) must be
provided
Sample integrity must be maintained
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
INVENTORY
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Physical evidence inventory
Case Reference data
Item number
Brief description
Where found
Witnesses
Serial numbers (if any)
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
GENERAL MARKING
PROCEDURES
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LARGE SOLID OBJECTS
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SMALL SOLID OBJECTS
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MARK WITH INITIALS
PLACE IN CONTAINER AND SEAL
MARK WITH INITIALS
LIQUIDS
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KEEP IN ORIGINAL CONTAINER
SEAL AND MARK
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
CHAIN OF CUSTODY RULE
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The party seeking to introduce into evidence
the results of examination of evidence has
the burden of proving that the specimen or
object is in fact derived from or taken from
the particular person or place.
This proof is customarily shown by testimony
which traces the location and custody of the
specimen.
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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CHRONICLE OF CUSTODY
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THE STEPS IN THE CHAIN INCLUDE
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THE INITIAL POSSESSION BY AN OFFICER
THE METHOD OF STORAGE
THE JOURNEY TO THE LAB
THE METHOD OF STORAGE AT LAB
THE POSSESSION OF UNUSED PORTION
UNTIL PRESENTED IN COURT
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Chain of Custody
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Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Edmond Locard (1877-1966)
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Demonstrated how Gross’ principles could be
incorporated into workable laboratory
Educated in Medicine and Law
1910 Lyons Police Dept. gave two rooms and two
assistants to start police laboratory
Initially had microscope and spectrometer
Founder and Director of Institute of Criminalistics
at the University of Lyon
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Principle of Exchange
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Locard's Principle of Exchange
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When a person comes in contact with an object or
another person, a cross-transfer of physical
material can occur.
The intensity, duration, and nature of the entities
and contact determine the extent of the transfer.
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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“Golden Rule” of Crime Scene
Investigation /Management
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“Never touch, change, or alter anything until
it has been documented, identified,
measured, and photographed … when a
body or article has been moved, it can never
be restored to its original position”
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
The Seven S’S of Crime-Scene
Investigation
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Securing the Scene
Separating the Witnesses
Scanning the Scene
Seeing the Scene
Sketching the Scene
Searching for Evidence
Securing and Collecting Evidence
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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FIRST OFFICER AT SCENE
ADMINISTER FIRST AID
 ARREST PERPETRATOR
 REQUEST AID
 DETAIN AND IDENTIFY WITNESSES
 SAFEGUARD CRIME SCENE
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Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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STEPS FOR SAFEGUARDING
THE SCENE
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DETERMINE CRIME SCENE AREA
EXCLUDE ALL PERSONS
BLOCK OFF BOUNDARIES
IDENTIFY AND SEGREGATE WITNESSES
NOTE DETAILS FOR LATER
AVOID UNNECESSARY WALKING ABOUT
DON’T TOUCH ANYTHING
PROVIDE INFORMATION TO INVESTIGATORS
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
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Cengage/NGL/South-Western © 2016
RECORD THE CRIME
SCENE
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Photography
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Sketching
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Notes
Forensic Science: Fundamentals & Investigations, 2e
Chapter 2
All rights Reserved
Cengage/NGL/South-Western © 2016