Download Evidence & The Crime Scene

Chapter 2 Crime Scene
Investigation and Evidence Collection
By the end of this chapter you will be able to:
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summarize Locard’s exchange principle
identify four examples of trace evidence
distinguish between direct and circumstantial evidence
identify the type of professionals who are present at a crime
scene
summarize the three steps of a crime scene investigation
explain the importance of securing the crime scene
identify the methods by which a crime scene is documented
demonstrate proper technique in collecting and packaging
trace evidence
describe how evidence from a crime scene is analyzed
All Rights Reserved South-Western / Cengage Learning © 2009
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Forensic Science: Fundamentals & Investigations, Chapter 2
Principle of Exchange
Dr. Edmond Locard, director of the world’s first
forensic lab (1910, Lyon, France), established
the idea of the exchange principle; namely that:
1. When a person comes in contact with an
object or another person, a cross-transfer of
physical material can occur.
2. Study of the material can determine the nature
and duration of the transfer.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Types of Evidence
 Statements of a witness in court would be
direct evidence.
 Indirect or circumstantial evidence, such as
a fingerprint (physical evidence) or blood or
hairs (biological evidence), would imply
something, and is called trace evidence.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Common types of trace evidence:
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Hair on clothes or rugs
Fingerprints
Soil
Drop of blood
Paint chips
Broken Glass
Fibers
Forensic Science: Fundamentals & Investigations, Chapter 2
Circumstantial Evidence
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Indirect evidence
Implies a fact, but does not prove it
Physical types?
Biological?
Forensic Science: Fundamentals & Investigations, Chapter 2
MORE Evidence Categories:
 Class
evidence - narrows an identity to a groups
of persons or things; ex. Blood type, hair color…
 Individual
evidence - evidence belonging to one
person or thing; ex. Fingerprints or DNA
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Forensic Science: Fundamentals & Investigations, Chapter 2
Class vs. Individual Evidence
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Forensic Science: Fundamentals & Investigations, Chapter 2
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These fibers are class
evidence; there is no way
to determine if they came
from this garment.
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The large piece of glass
fits exactly to the bottle; it
is individual evidence.
Types of Evidence
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This evidence was taken from a crime scene.
Is it Direct or circumstantial evidence?
Physical or biological evidence?
Class or individual evidence?
Explain why this would be or would not be trace
evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2
The Crime Scene
Investigation Team
Who is at the crime scene?
 Police (first to arrive) and possibly a district
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attorney (search warrant).
Crime scene investigators.
Medical examiners.
Detectives.
Specialists.
Forensic Science: Fundamentals & Investigations, Chapter 2
The Medical Examiner and the
Coroner
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A medical examiner is a medical doctor, usually a
pathologist and is appointed by the governing body of
the area. There are 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.
Forensic Science: Fundamentals & Investigations, Chapter 2
Goals of crime-scene
investigation:
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Recognize evidence
Document evidence
Collect evidence
Solving the crime depends on piecing the evidence
together in order to form a picture of what occurred
at the crime scene
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Forensic Science: Fundamentals & Investigations, Chapter 2
The Seven S’s of Crime Scene
Investigation
Secure the scene.
Separate the witnesses.
Scan the scene.
See to it that the crime scene examiners
receive overall and close up photos with
and without measuring rulers.
5. Sketch the scene.
6. Search for evidence.
7. Secure the collected evidence.
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4.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Packaging the evidence
Crease a clean paper and place the evidence in
the X position (as shown above).
2. Fold in the left and right sides, and then fold in
the top and bottom.
3. Put the bindle into a plastic or paper evidence
bag affixing a seal over the opening.
4. Write your name on the seal.
1.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Practice makes perfect…
Fold your own bindle!!!
Use a white piece of
paper and seal it up!!!
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Things to know:
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Liquids and arsons stored in airtight
containers
Biological evidence is stored in breathable
containers so it can dry without mold
Control samples should be collected, if
possible, for analysis at the lab
Why should samples from the victim be
collected?
Forensic Science: Fundamentals & Investigations, Chapter 2
Chain of Custody
1.
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In order to present credible evidence in court, a chain
of custody log is essential.
A person bags the evidence, marks it for identification,
seals it, and signs it across the sealed edge (above, left).
It is signed over to a technician in a lab for analysis who
opens it, but not on the sealed edge.
After analysis, the technician puts it back in the evidence
bag, seals it in another bag, and signs the evidence log
(above, right).
Forensic Science: Fundamentals & Investigations, Chapter 2
Analyze the Evidence
 The facts of the case are determined
when the forensic lab processes all the
collected evidence.
 The lab then sends the results to the lead
detective who aims to see how it all fits
into the crime scenario.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Analyze the Evidence
The lab results can:
 Show how reliable are any witness
accounts.
 Establish the identity of suspects or
victims.
 Show suspects to be innocent or link
them with a scene or victim.
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Forensic Science: Fundamentals & Investigations, Chapter 2
. . . . . . Summary to this point . . .
 Locard’s exchange principle: contact between
people and objects can transfer material that can
determine the nature and duration of the transfer.
 Evidence can be direct or indirect (physical or
biological traces).
 A crime scene investigation team consists of
police, detectives, crime scene investigators,
medical investigators, and specialists.
 The investigation consists of recognizing,
documenting, and collecting evidence.
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Forensic Science: Fundamentals & Investigations, Chapter 2
The Value of Physical
(Circumstantial) Evidence
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Generally more reliable than testimonial (direct) evidence
Can be used to prove that a crime has been committed
Can corroborate or refute testimony
Can link a suspect with a victim or with a crime scene
Can establish the identity of persons associated with a
crime
Can allow reconstruction of events of a crime
Forensic Science: Fundamentals & Investigations, Chapter 2
Types of Physical
(Circumstantial) Evidence
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Transient Evidence—temporary; easily changed or lost; usually
observed by the first officer at the scene
Pattern Evidence—produced by direct contact between a person and
an object or between two objects
Conditional Evidence—produced by a specific event or action;
important in crime scene reconstruction and in determining the set of
circumstances or sequence within a particular event
Transfer Evidence—produced by contact between person(s) or
object(s), or between person(s) and person(s)
Associative Evidence—items that may associate a victim or suspect
with a scene or each other; ie, personal belongings
—Lee and Labriola in Famous Cases, 2001
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Forensic Science: Fundamentals & Investigations, Chapter 2
Examples of Transient Evidence
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Odor—putrefaction, perfume, gasoline, urine, burning,
explosives, cigarette or cigar smoke
Temperature—surroundings, car hood, coffee, water in a
bathtub, cadaver
Imprints and indentations—footprints, teeth marks in
perishable foods, tire marks on certain surfaces
Markings
Forensic Science: Fundamentals & Investigations, Chapter 2
Examples of Pattern Evidence
Pattern Evidence—most are in the form of imprints,
indentations, striations, markings, fractures or deposits.
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Blood spatter
Glass fracture
Fire burn pattern
Furniture position
Projectile trajectory
Tire marks or skid marks
Forensic Science: Fundamentals & Investigations, Chapter 2
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Clothing or article
distribution
Gun powder residue
Material damage
Body position
Tool marks
Modus operandi
Examples of Conditional Evidence
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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
Location—of injuries or
wounds, of bloodstains, of
the victim’s vehicle, of
weapons or cartridge cases,
of broken glass
Forensic Science: Fundamentals & Investigations, Chapter 2
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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
Classification of Circumstantial
Evidence by nature:
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Biological—blood, semen, saliva, sweat, tears, hair, bone,
tissues, urine, feces, animal material, insects, bacterial, fungal,
botanical
Chemical—fibers, glass, soil, gunpowder, metal, mineral,
narcotics, drugs, paper, ink, cosmetics, paint, plastic, lubricants,
fertilizer
Physical—fingerprints, footprints, shoe prints, handwriting,
firearms, tire marks, tool marks, typewriting
Miscellaneous—laundry marks, voice analysis, polygraph,
photography, stress evaluation, psycholinguistic analysis, vehicle
identification
Forensic Science: Fundamentals & Investigations, Chapter 2
Forensics Investigations
Include some OR all of these seven major activities
1. Recognition—ability to distinguish important evidence
from unrelated material
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Pattern recognition
Physical property observation
Information analysis
Field testing
2. Preservation—collection and proper preservation of
evidence
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Forensic Science: Fundamentals & Investigations, Chapter 2
Forensics Investigations (cont’d)
3. Identification—use of scientific testing
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Physical properties
Chemical properties
Morphological (structural) properties
Biological properties
Immunological properties
4. Comparison—class characteristics are measured against
those of known standards or controls; if all
measurements are equal, then the two samples may be
considered to have come from the same source or
origin.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Forensics Investigations
5. Individualization—demonstrating that the sample is
unique, even among members of the same class
6. Interpretation—gives meaning to all the information
7.
Reconstruction—reconstructs the events of the case
It involves:
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forming a hypothesis of the sequence of events from before the
crime was committed through its commission.
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The evidence and witness statements need to fit the overall crime
scenario
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Evidence does not lie but it could be staged
—Lee, Dr. Henry. Famous Crimes, 2001
Forensic Science: Fundamentals & Investigations, Chapter 2
The Crime Scene
“Oh, how simple it would all
have been had I been here
before they came like a
herd of buffalo and
wallowed all over it.”
—A. Conan Doyle, in The Boscombe
Valley Mystery, 1892
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Forensic Science: Fundamentals & Investigations, Chapter 2
Staged Crime Scenes
When the lab results do not match up with the
testimony of witnesses, it can mean the crime
was staged; common examples include:
 Staging a fire—to cover bankruptcy.
 Staging a suicide—to cover a murder.
 Staging a burglary—to collect insurance
money.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Staged Crime Scenes
To help determine whether a crime scene
was staged, consider:
 Whether the type of wound found on the
victim matches the weapon employed.
 Whether the wound could have been easily
self-inflicted.
 The mood and actions of the victim before
the event.
 The mood and actions of a suspect before
the event.
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Forensic Science: Fundamentals & Investigations, Chapter 2
CORPUS Delicti
“Body of Crime”
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Before a person can be convicted of a crime, You must prove…
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Top Reasons for Committing a Crime
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Money
Revenge
Emotion—love, hate, anger
Source of Evidence
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that a crime occurred
that the person charged with the crime was responsible for the crime
Body
Primary and/or Secondary Crime Scene
Suspect(s)
Forensic Science: Fundamentals & Investigations, Chapter 2
First Officer on the Scene
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Forensic Science: Fundamentals & Investigations, Chapter 2
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Assess the crime scene
and assist those hurt
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Detain the witness
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Arrest the perpetrator
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Protect the crime scene
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T
Take notes
Crime Scene Survey
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Walk-through—may be performed by the first officer, the CSI, and/or
sometimes the lead detective
Purpose:
 Note any transient or conditional evidence that could change over
time.
 Note weather conditions
 Note points of entry or exit, as well as paths of travel within the
crime scene
 Record initial observations of who, what, where, when, and how
 Identify special needs within the crime scene for personnel,
precautions or equipment and notify superior officers or other
agencies
 After initital examination, mentally prepare a reconstruction theory
Forensic Science: Fundamentals & Investigations, Chapter 2
Documentation
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Notes—date and time, description of the location, weather and
environmental conditions, description of the crime, location of
the evidence relative to other key points, the names of all people
involved, modifications that have occurred and other relevant
information
Photography—photos of scene and surroundings, mid-range to
close-up photos with various angles of each piece of evidence,
photos as viewed by any witnesses.
Sketches—inclusion of date, time, scale, reference points,
distance measurements, names of investigators, victims,
suspects, and a legend (key)
Videography—allows narration (non-subjective) to be included
Forensic Science: Fundamentals & Investigations, Chapter 2
Searching Methods
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Line or strip method—best in large, outdoor scenes
Grid method—basically a double-line search; effective, but timeconsuming
Zone method—most effective in houses or buildings; teams are
assigned small zones for searching
Wheel or ray method—best on small, circular crime scenes
Spiral method—may move inward or outward; best used where there
are no physical barriers
Forensic Science: Fundamentals & Investigations, Chapter 2
Crime Scene Sketch
Date: August 14, 2005
Time: 11:35 am
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Forensic Science: Fundamentals & Investigations, Chapter 2
Criminalist: Ann Wilson
Location: 4358 Rockledge Dr, St. Louis, Mo.
Collecting and Packaging
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One individual should be designated as the evidence collector to
ensure that the evidence is collected, packaged, marked, sealed,
and preserved in a consistent manner
Each item must be placed in a separate container, sealed, and
labeled
Most fragile is collected and packaged first
Different types of evidence require specific or special collection and
packaging techniques
The body is the property of the coroner or medical examiner. The
collection of evidence on the body is done by that department
Forensic Science: Fundamentals & Investigations, Chapter 2
Packaging
Most items should be packaged in a primary
container and then placed inside a
secondary one. These are then placed
inside other containers such as paper
bags, plastic bags, canisters, packets and
envelopes depending on the type and
size of the evidence.
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Forensic Science: Fundamentals & Investigations, Chapter 2
Chain of Custody
There must be a written record of all people who
have had possession of an item of evidence.
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The evidence container must be marked for identification
The collector’s initials should be placed on the seal
If evidence is turned over to another person, the transfer
must be recorded.
Forensic Science: Fundamentals & Investigations, Chapter 2
Investigators
There must be a written record of all people who have
had possession of an item of evidence.
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The evidence container must be marked for identification
The collector’s initials should be placed on the seal
If evidence is turned over to another person, the transfer
must be recorded.
Forensic Science: Fundamentals & Investigations, Chapter 2
Medical Examiner’s Responsibility
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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
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Natural
Accidental
Suicide
Homicide
Undetermined
Notify the next of kin
Forensic Science: Fundamentals & Investigations, Chapter 2
The Corspe
“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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Forensic Science: Fundamentals & Investigations, Chapter 2
. . . . . . . . . . . . . . . . . Summary
 First responding officers identify the extent of the
crime scene, secure it, and segregate witnesses.
 Crime scene investigators document the crime
scene.
 Evidence must be collected, packaged, and
labeled.
 The evidence then is analyzed and interpreted to
fit the crime scenario.
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Forensic Science: Fundamentals & Investigations, Chapter 2
More Information
For additional information on crime scene investigation, check out
Court TV’s Crime Library:
www.crimelibrary.com/criminal_mind/forensics/crimescene/5.html
On Michael Baden and the autopsy:
www.crimelibrary.com/criminal_mind/forensics/autopsy/1.html
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Forensic Science: Fundamentals & Investigations, Chapter 2