FORENSIC SCIENCE by Sm5dWLv

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									FORENSIC
 SCIENCE



INTRODUCTION to
   Crime Scene
   Investigation
      CRITICAL
      THINKING
When Mrs. Jackson came
back from lunch, there were
several messages on her desk.
By changing each digit of the
phone numbers to one of the
three corresponding letters on
the telephone buttons, can
you determine from whom
each message came?


                          2
              Answers
         to Critical Thinking
336-8478           dentist
(222)686-8268      accountant
774-6837           printer
487-2263           husband
247-5463           airline
832-2437           teacher


                                 3
                   Forensic Science
Definition: The application of scientific technology to
   supply accurate and objective information reflecting
   the events that occurred at a crime.

         What does a Forensic Scientist DO???
1. Analyze physical evidence
2. Provide Expert Testimony
3. Provide training in the recognition, collection and
   preservation of physical evidence
                                                          4
Complex Reasoning
In Forensic Science
          Deductive (reasoning from
           the general to the particular)
           and
          Inductive Reasoning
           (reasoning from detailed
           facts to general principles)
          Classifying
          Comparing and Contrasting
          Problem Solving
          Analyzing Perspectives
          Constructing Support
          Error Analysis
  Locard’s Exchange Principle

Whenever 2 objects come in contact with
 one another, they exchange some material
 (dust particles, hair, dead skin cells…)
Locard strongly believed that every
 criminal can be connected to a crime by
 dust particles carried from the scene


                                            6
            Forensic Pathology
Investigation of sudden unnatural, unexplained
 or violent deaths
Answer the questions:
  Who is the victim?
  What are the injuries, when did they occur, and
   how were they produced?
5 manners of death: natural, homicide, suicide,
 accident, undetermined

                                                     7
                            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
                                                                       8
                  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


                                  9
                  Eye Witness
“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.
(Eye Witness Activity)           Faces Composite Program
                                 by InterQuest
                                                           10
               Crime Scene
              Search Patterns
TWO of FOUR PATTERNS

Spiral                Grid




                                11
                  Crime Scene
                 Search Patterns
TWO of FOUR PATTERNS

Strip or Line         Quadrant or Zone




                                           12
                        Crime Scene
                           Sketch
Date: August 14, 2001                    Criminalist: Ann Wilson
Time: 11:35                              Location: 4358 Rockledge Dr
                                                    St. Louis, Mo.



  A. Couch/sofa
                                                 E
  B. Female body                 c
                                                 D
  C. Knife
                                                                       G
  D. Over turned Lamp                A

  E. Chairs              E
  F. Table                                        E
                                                 E
  G. Fireplace               F                                   E



                                                                           13
 Physical Evidence
Transient Evidence--temporary;
    easily changed or lost; usually
    observed by the first officer at the
    scene
   Odor--putrefaction, perfume,
    gasoline, urine, burning, explosives,
    cigarette or cigar smoke
   Temperature--of room, car hood,
    coffee, water in a bathtub; cadaver
   Imprints and indentations--footprints;
    teeth marks in perishable foods; tire
    marks on certain surfaces
   Markings
                                         14
         Physical Evidence (cont)
Pattern or Transfer Evidence--
  produced by direct contact
  between a person and an object
  or between two objects.




                                    15
          Physical Evidence (cont)
Conditional Evidence--produced by
  a specific event or action; important
  in crime scene reconstruction and in
  determining the set of circumstances
  within a particular event.
   Light--headlight; lighting
      conditions
   Smoke--color, direction of travel,
      density, odor
   Fire--color and direction of the
      flames, speed of spread,
      temperature and condition of fire
                                          16
         Conditional Evidence (cont.)
Location--of injuries or wounds; of bloodstains; of the
 victims vehicle;of weapons or cartridge cases; of
 broken glass, etc.
Vehicles--doors locked or unlocked, windows opened
 or closed; radio off or on (station); odometer mileage
Body--position; types of wounds; rigor, livor and algor
 mortis
Scene--condition of furniture, doors and windows; any
 disturbance or signs of a struggle.

                                                       17
                        Evidence
                      Characteristics
Class--common to a group of objects or persons

Individual--can be identified with a particular person or
  source.

       ABO Blood Typing               Blood DNA Typing




                                                            18
                   Medical Examiner vs
                       the Coroner

A medical examiner is a medical doctor, usually a
  pathologist and is appointed by the governing body of
  the area. There are 7 medical examiners in the state of
  Missouri and 400 forensic pathologists throughout the
  U.S.
A coroner is an elected official who usually has no
  special medical training. In four states the coroner is a
  medical doctor.

                                                          19
                           Medical Examiner’s
                            Responsibilities
 Identify the deceased
 Establish the time and date of death
 Determine a medical cause of death--the injury or disease that resulted in
   the person dying
 Determine the mechanism of death--the physiological reason that the
   person died
 Classify the manner of death
       Natural
       Accidental
       Suicide
       Homicide
       Undetermined
 Notify the next of kin
                                                                               20
              THE BODY
              Rigor Mortis

Temperature     Stiffness        Time Since
  of body       of body            Death

  •Warm         •Not stiff   •Not dead more than 3 hrs

  •Warm         •Stiff       •Dead between 3 and 8 hrs

  •Cold         •Stiff       •Dead 8 to 36 hours

  •Cold         •Not stiff   •Dead more than 36 hours


                                                         21
                   THE BODY
                      Livor Mortis
Livor mortis is the settling of the blood, causing the skin
  to change colors.

Lividity indicates the position of the body after death.
  When lividity becomes fixed, then the distribution of
  the lividity pattern will not change even if the body’s
  position is altered.

Lividity usually becomes fixed between 10 and 15 hours
  after death.
                                                            22
             THE BODY
                Algor Mortis

      Algor mortis is body temperature.

Average human body temperature: 98.6 F (37 C)




                                                23
             Time Frame of Death
   Condition                             Appearance
     Peripheryblood drying            30 min to 2 hrs
     Blue-green discoloration of skin
        Right and left area of abdomen   24 hours
        Entire abdomen                   36 hours
     Bloating                            36 to 48 hours
     Skinslippage                        4 to7 days
     Absence of smell from bones         more than 1 year

                                                             24
              Time Frame of Death
                    Eyeball Changes
 Condition                         Appearance
   Cornea drying (eyes open)        minutes
   Cornea drying (eyes closed)      2 hours
   Corneal cloudiness (eyes open) less than 2 hours
   Corneal cloudiness (eyes closed) 12 to 24 hours
   Eyeball collapse                 more than 24 hrs




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                 THEREFORE,
       One can die of a massive hemorrhage (the
mechanism of death) due to a fall (cause of death) as a
result of being pushed (homicide), jumping (suicide),
falling (accident), or not being able to tell which
(undetermined). All of which are manners of death.




                                                          26
             FACETS OF GUILT
Means--the ability of have committed the crime
Motive--the reason for committing the crime.
 (This doesn’t have to be proven or presented in
 a court of law, but its what everyone wants to
 know.)
Opportunity--time or availability to have
 committed the crime.


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Just A Thought

    It’s not what you know
       that hurts you, its what
       you think you know
       and it’s not so        .
       . . . .Mark Twain

    How does this apply to
     forensic science and crime
     investigations?          28

								
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