FORENSIC SCIENCE

1
FORENSIC SCIENCE

• INTRODUCTION
• Crime Scene
• Investigation

2
Forensic Science

• Definition
• The application of science to those criminal and
  civil laws that are enforced by police agencies
  in a criminal justice system.
• The business of providing timely, accurate, and
  thorough information to all levels of decision
  makers in our criminal justice system.

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Complex ReasoningIn Forensic Science

• Deductive and Inductive Reasoning
• Classifying
• Comparing and contrasting
• Problem Solving
• Analyzing Perspectives
• Constructing Support
• Error Analysis

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CRIME
Why Did It Happened?
Who Did It?
What Happened?
Crime Scene Evidence Collection Witness,
Suspect and Motive Development
Investigative Stage Profiling Means
Motive Opportunity
Identification and Arrest of Suspect


Post Scene Evidence Processing Cause,
manner, time of death
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CORPUS DELICTI Body of the Crime

• You must prove
• that a crime occurred
• that the person charged with the crime was
  responsible for the crime
• Top Reasons for Committing a Crime
• Money
• Revenge
• Sex
• Emotion--love, hate, anger
• Source of Evidence
• Body
• Primary and/or Secondary Crime Scene
• Suspect(s)

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Crime Scene Team

• A group of professionals investigators, each
  trained in a variety of special disciplines.
• Team Members
• First Police Officer on the scene
• Medics (if necessary)
• Investigator(s)
• Medical Examiner (if necessary)
• Photographer and/or Field Evidence Technician
• Lab Experts
• pathologist serologist
• DNA expert toxicologist
• forensic odontologist forensic anthropologist
• forensic psychologist forensic entomologist
• firearm examiner bomb and arson expert
• document and handwriting experts fingerprint
  expert

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First Officer at the Scene

• A Assess the crime scene
• D Detain the witness
• A Arrest the perpetrator
• P Protect the crime scene
• T Take notes for CSI team

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Eye Witness

• Will explain their part of the scene
• Give enough information to lead the team to a
  conclusion about what happened at this crime
  scene
• Perception is reality.
• As a result an eye witness may not be the best
  source of crime scene information.
• A police composite may be developed from the
  witness testimony by a computer program or
  forensic artist.

Faces Composite Program by InterQuest
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Basic Stages in a Search These
are the responsibility of the 1st Officer at the
scene.

• Approach, secure and protect the scene
• Initiate preliminary survey/determine scene
  boundaries
• Only authorized personnel should be allowed on
  the scene (Every person who enters the scene is
  a potential contaminator of viable physical
  evidence)
• Once a scene is secured, the lead investigator
  duties
• Evaluate physical evidence possibilities
• Prepare narrative description
• Depict scene photographically
• Prepare diagram/sketch of scene
• Conduct detailed search
• Record and collect physical evidence
• Conduct final survey
• Release scene

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Photography

• Scene should be photographed in an unaltered
  condition. Unless someone is injured, everything
  should be left in its unaltered condition.
• Close-up of phys. evidence should include a ruler
  or something to show size/scale
• Videotaping/digital cameras
• Still photography is still the best for its
  detail
• WHAT to photograph?
• Area of crime
• Adjacent areas
• Entrance/exit
• Body if present -- area under body after removal
• injuries/ weapons

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ROUGH Sketches

• After photos, sketch first rough sketch is made
  at the scene
• Accurate depiction of the dimensions at the scene
• Location of important objects to the case
• TRIANGULATION METHOD measured accurately
• Each object is given a letter and a legend or
  list will correlate the letter to the item
• Designate north on the sketch
• ( The finished sketch is drawn to scale using the
  measurements provided in the rough sketch and is
  used as court evidence)

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HOW do you do a proper sketch?

• Lay out basic perimeter
• Windows, doors, etc
• Set forth fixed objects, furniture, etc
• Record position of evidence
• Appropriate measurements double check
• Key/legend, compass orientation, etc
• NOTES
• Constant activity throughout the processing of
  the scene
• Detailed description of the scene with location
  of evidence recovered
• Must id the time the evidence was discovered,
  whom, how, and then packaged, marked after
  collected
• Tape recording notes is helpful, but would need
  to be transcribed.

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Typical material found on rough sketch

Specific location Date Time
Case identifier Preparer Weather conditions
Lighting conditions Scale or disclaimer Compass orientation
Evidence Measurement Key or legend
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Crime SceneSketch
Date August 14, 2001 Criminalist Ann
Wilson Time 1135 Location 4358 Rockledge
Dr St. Louis, Mo.
A. Couch/sofa B. Female body C. Knife D. Over
turned Lamp E. Chairs F. Table G. Fireplace
E
c
D
G
A
E
E
E
E
F
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TRIANGULATION
Measure from A to B and then to the evidence in a
triangular shape. AB need to be fixed points,
something that will not change!
Examples of a fixed point - windows -
doors - trees - buildings
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MAPPING TECHNOLOGY

• The latest technology includes this Nikon Tsunami
  with computer. The exact location of all crime
  evidence can be determined and directly loaded
  into a computer to produce a crime scene map.
• (Cost 35,000 for the set)

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Can we search for evidence now?

• Edmond Locard - French professor
• Considered the Father of Criminalistics
• Built the worlds first forensic laboratory in
  France in 1910
• Locard Exchange Postulate
• Whenever two objects come into contact with each
  other, traces of each are exchanged.

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FOUR BASIC PREMISES

• The best search options are typically the most
  difficult and time consuming
• You can not over document the physical
  evidence.
• There is only one chance to perform the job
  properly
• There are two basic search approaches
• A cautious search of visible areas, taking
  steps to avoid evidence loss or contamination
• After the cautious search, a vigorous search
  for hidden/concealed areas.

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The Search.

• A search must always be thorough and systematic
  (even if a suspect is guilty!)
• Methods of search are always customized to suit
  the crime. (Ex. Large open area uses a line
  search with a few people)
• Here are some factors that help determine the
  type of search method
• - Locale and size of area
• - of techs available
• - size/type of evidence

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Crime Scene Search Patterns
TWO of FOUR PATTERNS

• Strip or Line

• Quadrant or Zone

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Crime Scene Search Patterns
TWO of FOUR PATTERNS

• Spiral

• Grid

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Collection

• The collection of evidence starts with the most
  fragile or most easily lost evidence.
• Photographs are continually taken.
• Most items are placed in paper envelopes or bags.
• Any liquid, arson evidence, or moist evidence are
  packaged differently, not in paper bags.
• Items are always packaged separately to eliminate
  cross-contamination.
• Proper labeling must always be place on ALL
  packages!

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WHAT GOES TO THE LAB?

• Physical evidence must be collected in such a way
  that prevents any change between the crime scene
  and the crime lab.
• Victims clothing- never in an airtight
  container.
• Fingernail scrapings
• Hairs- leave on the article and send entire
  article to lab, where they will remove the hair
• Blood- leave on the article and send entire
  article to lab, where they will remove the blood
• Never in an airtight container, because the
  condensation could cause mold growth which could
  destroy the evidence.
• Fibers- leave on the article and send entire
  article to lab, where they will remove the fibers
• Swabs of secretions
• Charred debris- should be packaged in an
  air-tight container, so the petroleum residues do
  not evaporate. (paint cans)
• Bullets
• Hand swabs if needed
• NOTE Each different item must be packaged
  separately! (prevent cross contamination)

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Just A Thought

• Its not what you know that hurts you, its what
  you think you know and its not so . .
  . . .Mark Twain
• How does this apply to forensic science and crime
  investigations?