FORENSIC
SCIENCE
INTRODUCTION
Crime Scene
Investigation
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
2
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
The History of Forensic Science
Sherlock Holmes: a fictional character developed by Sir Arthur
Conan Doyle; used a great deal of forensic detection
Mathieu Orfila: toxicology (the detection of poisons)
Alphonse Bertillon: anthropometry (personal identification
through body measurements)
Francis Galton: developed 1st fingerprint identification system
Leone Lattes: determined methods of using blood type as a
means of identification
Calvin Goddard: firearms examination
Albert Osborn: document examination
Edmund Locard: Developed the 1st police lab
J. Edgar Hoover: director of the FBI: Organized the 1st FBI
Crime Lab in 1932
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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
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Branches of Forensic Science
Physical science: Using chemistry, physics,
and geology to ID and compare crime scene
evidence
Biology: blood, body fluids, hairs and fibers,
entomology
Pathology, psychology, odontology, any many
more!
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CORPUS DELICTI
You must prove:
“Body of the Crime”
 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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4 Major FEDERAL Crime Labs:
FBI
Drug Enforcement Administration (DEA)
Bureau of Alcohol, Tobacco, Firearms and
Explosives (ATF)
US Postal Inspection Service
Most states also have their own, smaller crime
labs
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General Crime Lab Services
and the materials each unit analyzes
Physical Science Unit: drugs, glass, paint, explosives,
etc
Biology Unit: blood and other bodily fluids
Firearms Unit: ballistics, comparisons
Document Examination Unit: handwriting,
typewriting, questioned documents (ransom notes, etc)
Photography Unit: record all phyhsical evidence.
Toxicology Unit: presence/absence of drugs
Latent Fingerprint Unit: fingerprints
Pathology Unit9
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
 GO TO SLIDE 25…..
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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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INVESTIGATORS
“The wise forensic investigator will always
remember that he must bring all of his life
experiences and logic to find the truth. This
means common sense, informed intuition, and
the courage to see things as they are. Then he
must speak honestly about what it adds up to.”
Dr. Henry Lee
Chief Emeritus for Scientific Services and the former Commissioner of Public Safety for
the state of Connecticut
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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
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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.
Faces Composite Program
by InterQuest
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Crime Scene
Search Patterns
TWO of FOUR PATTERNS
Spiral
Grid
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Crime Scene
Search Patterns
TWO of FOUR PATTERNS
Strip or Line
Quadrant or Zone
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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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Crime Scene Mapping
(outdoors)
Azimuth--uses a compass beam to determine
the location of each piece of evidence
Triangulation--uses two points at the crime
scene to map each piece of evidence
Coordinate or grid--divides the crime scene into
squares for mapping.
Suspended Polar Coordinate--for use in
mapping evidence in a hole
Baseline--set a north/south line and measures
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each piece of evidence from this line.
AZIMUTH
Determines:
•Direction
•Distance
•Elevation
TRIANGULATION
Measure from A to B
and then to the
evidence in a
triangular shape.
Coordinate or
Grid Mapping
Set a north/south
line from a datum
point established
by a GPS.
Make it a perfect square (4 x 4)
by shooting the hypotenuse
and setting in stakes every foot
or meter.
Measure and map
the location of each
piece of evidence.
Then collect
evidence and place
in containers by
grid.
Baseline Mapping
Set a north/south line from
the furthest most points
of the crime scene. Then
measure each piece of
evidence from that
baseline. Evidence will
need a numerical
measurement where the
piece begins, ends and in
the middle.
Evidence
Baseline
Suspended Polar
Coordinate
Measure and map each
layer of evidence as
you move down the
hole. Use the
compass readings
from the top to
measure degrees and
a tank dipping line to
measure depth.
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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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. There
are several ways (at least 7) of
classifying evidence. In this
class, we will use:
Biological
Chemical
Physical
Miscellaneous
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Biological Evidence
Blood
Semen
Saliva
Sweat/Tears
Hair
Bone
Tissues
Urine
Feces
Animal Material
Insects
Bacterial/Fungal
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Chemical Evidence
Fibers
Glass
Soil
Gunpowder
Metal
Mineral
Narcotics
Drugs
Paper
Ink
Cosmetics
Paint
Plastic
Lubricants
Fertilizer
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Physical (impression)
Fingerprints
Footprints
Shoe prints
Handwriting
Firearms
Printing
Number restoration
Tire marks
Tool marks
Typewriting
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Miscellaneous
Laundry marks
Voice analysis
Polygraph
Photography
Stress evaluation
Pyscholinguistic analysis
Vehicle identification
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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
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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.
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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
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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.
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THE BODY
Algor Mortis
Algor mortis is body temperature.
Average human body temperature: 98.6 F (37 C)
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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
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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.
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CRIME
Why Did It
Happened?
What
Happened?
Crime Scene
Evidence Collection
Witness, Suspect and
Motive Development
Post Scene
+
Investigative Stage
Profiling
Means
Motive
Opportunity
Who Did
It?
=
Identification
and Arrest of
Suspect
Evidence Processing
Cause, manner, time
of death
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Forensic Investigations
Include some or all of these seven major activities
Recognition--ability to distinguish important
evidence from unrelated material
Pattern recognition
Physical property observation
Information analysis
Field-testing
Preservation--collection and proper preservation of
evidence
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Investigations (cont)
Identification--use of scientific testing
Physical properties
Chemical properties
Morphological (structural) properties
Biological properties
Immunological properties
Comparison--class characteristics are measured against
those of know standards or controls; If all
measurements are equal, then the two samples are
considered to have come from the same source or
origin.
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Investigations (cont.)
Individualization--demonstrating that the sample is
unique, even among members of the same class.
Interpretation--gives meaning to all the information
Reconstruction--reconstructs the case events
Inductive and deductive logic
Statistical data
Pattern analysis
Results of laboratory analysis
Lee, Dr. Henry. Famous Crimes. Southington:Strong Books, 2001
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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
46
investigations?