Transcript FORENSIC SCIENCE

FORENSIC
SCIENCE
INTRODUCTION
Crime Scene
Investigation
UNITS
FIRST SEMESTER
Introduction
Physical Evidence
DNA
Documentation
Biology
SECOND SEMESTER
Introduction
Prints
Toxicology
Trace Evidence
Serology
2
Forensic Science
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 decisions makers in our
criminal justice system.
3
Complex Reasoning
In Forensic Science
Deductive and Inductive
Reasoning
Classifying
Comparing and
Contrasting
Problem Solving
Analyzing Perspectives
Constructing Support
Error Analysis
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)
5
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
6
CRIME LAB
HISTORY
First police crime lab in the world was established
in France in 1910 by Edmond Locard
First police crime lab in the U.S. opened in 1924
The Scientific Crime Detection Lab was founded
in Evanston, Illinois in 1929
The first FBI crime lab opened in 1932
7
Edmond Locard
French professor
Considered the father of criminalistics
Built the world’s first forensic laboratory in
France in 1910
Postulate--Locard Exchange Postulate
Whenever two objects come into contact with each other,
traces of each are exchanged.
8
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
9
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
10
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
11
A TRUE EYEWITNESS
Crazy Criminal
As a female shopper exited a New York
convenience store, a man grabbed her purse
and ran. The clerk called 911 immediately and
the woman was able to give them a detailed
description of the snatcher. Within minutes, the
police had apprehended him. They put him in
the car and drove back to the store. The thief
was then taken out of the car and told to stand
there for a positive ID. With that he replied,
“Yes, Officer. . That’s her. That’s the lady I
stole the purse from.”
12
Crime Scene
Search Patterns
TWO of FOUR PATTERNS
Spiral
Grid
13
Crime Scene
Search Patterns
TWO of FOUR PATTERNS
Strip or Line
Quadrant or Zone
14
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
15
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
16
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.
22
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
23
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
24
Biological Evidence
Blood
Semen
Saliva
Sweat/Tears
Hair
Bone
Tissues
Urine
Feces
Animal Material
Insects
Bacterial/Fungal
25
Chemical Evidence
Fibers
Glass
Soil
Gunpowder
Metal
Mineral
Narcotics
Drugs
Paper
Ink
Cosmetics
Paint
Plastic
Lubricants
Fertilizer
26
Physical (impression)
Fingerprints
Footprints
Shoe prints
Handwriting
Firearms
Printing
Number restoration
Tire marks
Tool marks
Typewriting
27
Miscellaneous
Laundry marks
Voice analysis
Polygraph
Photography
Stress evaluation
Pyscholinguistic analysis
Vehicle identification
28
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
29
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.
30
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.
31
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.
32
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
34
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.
35
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
36
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.
37
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
38
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
39
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.
40
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
41
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
42
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
43
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.
44
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
45
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
46
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.
47
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
48
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
49
investigations?