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
5
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 37…..
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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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Cadaver Dogs
Dogs with a sense of smell
100 times better than
humans can sometimes find
what would be overlooked.
They are specially trained
to locate injured, lost
and/or deceased
individuals. They are
trained as air scent dogs or
article (cloth) scent dogs.
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Cadaver Dogs
www.moregionck9search-rescue.com
Dogs are trained to
locate human body
fluids including blood,
hair, teeth, urine, and
semen. The dog on
the left in a training
exercise is trying to
locate clothing with
blood.
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Cadaver Dogs
Looking at a crime scene, humans would probably miss
something as small as this tooth. The dog found it within
minutes of searching the scene.
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 Autopsy
Y incision from the left shoulder, down under the nipples and over
to the right shoulder. Then place the scalpel in the pit of the
abdomen, below the sternum and cut straight down and left of
the belly button.
Two Methods for Organ Removal--named for two German
pathologists
Rokitansky procedure:organs all come out at once.
Virchow procedure: each organ is removed separately and
immediately examined.
A second incision of the body circumnavigates the skull from earto-ear behind the head.
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The Corpse
“The way I see it, being dead is not terribly
far off from being on a cruise ship. Most
of your time is spent lying on your back.
The brain has shut down. The flesh begins
to soften. Nothing much new happens,
and nothing is expected of you.”
--Mary Roach. Stiff. W. W. Norton & Company. 2003
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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. At a crime scene, it
can be obtained in two different ways.
Rectal temperature
Liver temperature
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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 gun shot wound
through the head (cause of death) as a result of being
shot (homicide), shooting yourself (suicide), dropping
a gun and it discharging (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
Who Did
It?
Investigative Stage
+
Profiling
Means
Motive
Opportunity
=
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
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investigations?