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
(222)686-8268
774-6837
487-2263
247-5463
832-2437
dentist
accountant
printer
husband
airline
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
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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
DNA expert
forensic odontologist
forensic psychologist
firearm examiner
document and handwriting experts
serologist
toxicologist
forensic anthropologist
forensic entomologist
bomb and arson expert
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
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
Time: 11:35
Criminalist: Ann Wilson
Location: 4358 Rockledge Dr
St. Louis, Mo.
A. Couch/sofa
E
c
B. Female body
D
C. Knife
D. Over turned Lamp
E. Chairs
E
F. Table
G. Fireplace
G
A
F
E
E
E
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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
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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
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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.
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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
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THE BODY
Rigor Mortis
Temperature
of body
Stiffness
of body
Time Since
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
 Periphery
blood drying
30 min to 2 hrs
 Blue-green discoloration of skin
 Right
and left area of abdomen
 Entire abdomen
 Bloating
 Skin
slippage
 Absence of smell from bones
24 hours
36 hours
36 to 48 hours
4 to7 days
more than 1 year
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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
25
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.
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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.
27
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
28
investigations?