Forensic Science
Mr. Snyder
Room S206
Kickapoo High School
M
E
E
T
M
R
S
N
Y
D
E
R
Class Website
http://rsnyder20.tripod.com
What is Forensic Science?
•
•
Forensic science is the application of natural sciences to matters of the law. In practice,
forensic science draws upon physics, chemistry, biology, and other scientific principles
and methods. Forensic science is concerned with the recognition, identification,
individualization, and evaluation of physical evidence. Forensic scientists present their
findings as expert witnesses in the court of law.
The word “forensic” means “pertaining to the law”; forensic science resolves legal
issues by applying scientific principles to them.
A Career in Forensic Science
• Must have a bachelor's degree, best if in chemistry, biology, or forensic science.
• Columbia College, Missouri, Southeast Missouri State University, Saint Louis
University School of Medicine, Saint Louis University, Oklahoma State University,
Arkansas State University, University of Arkansas, Little Rock
• Starting Salaries range from $30,000- $35,000 a year to $80,000-$120,000 a year
with 20 years experience.
Units of a Forensics Team
Physical Science Unit
Biological Unit
• Chemistry (drugs,
explosives)
• Physics (glass, scratches)
• Geology (soil, rocks)
•
•
•
•
Firearms Unit
Photography Unit
• Firearms
• Bullets
• Cartridge & Shells
• Ammunition
• Garments
• Records the crime scene
• Photographs
• Sketches
• Notes
Bloodstains
Body fluids
Hair and fiber
Botanical materials (wood
and plants).
Part 1: Crime Scene Basics
Approaching a Crime Scene Protocol
• Personal Safety and the well being of
victims
• Preserve and Isolate the crime scene
• Record the crime scene
Crime Scene Vocabulary
CRIME SCENE: Any physical location in which a crime has occurred or is
suspected of having occurred.
PRIMARY CRIME SCENE: The original location of a crime or
accident.
SECONDARY CRIME SCENE: An alternate location where
additional evidence may be found.
SUSPECT: Person thought to be capable of committing a crime.
ACCOMPLICE: Person associated with someone suspected of committing a crime.
ALIBI: Statement of where a suspect was at the time of a crime.
Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm
Types of Evidence
Testimonial evidence includes oral or written statements given to police as well as
court testimony by people who witnessed an event.
Physical evidence refers to any material items that would be present at the crime
scene, on the victims, or found in a suspect’s possession.
Trace evidence refers to physical evidence that is found in small but measurable
amounts, such as strands of hair, fibers, or skin cells.
What will evidence collected at a scene do for the investigation?
• May prove that a crime has been committed
• Establish key elements of a crime
• Link a suspect with a crime scene or a victim
• Establish the identity of a victim or suspect
• Corroborate verbal witness testimony
• Exonerate the innocent.
• Give detectives leads to work with in the case
Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm
Crime Scene Personnel
POLICE OFFICERS are typically the first to arrive at a crime scene. They are
responsible for securing the scene so no evidence is destroyed and detaining
persons of interest in the crime.
The CSI UNIT documents the crime scene in detail and collects any physical
evidence.
The DISTRICT ATTORNEY is often present to help determine if any search
warrants are required to proceed and obtains those warrants from a judge.
The MEDICAL EXAMINER (if a homicide) may or may not be present to
determine a preliminary cause of death.
SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be
called in if the evidence requires expert analysis.
DETECTIVES interview witnesses and consult with the CSI unit. They
investigate the crime by following leads provided by witnesses and physical
evidence.
Source: http://science.howstuffworks.com/csi.htm
Crime Scene Protocol
Step 1: Interview
The first step in investigating a crime scene is to interview the first officer at the scene or the
victim to determine what allegedly happened, what crime took place, and how was the crime
committed. This information may not be factual information but it will give the investigators a
place to start.
Step 2: Examine
The second step in the investigation of a crime scene, which will help identify possible
evidence, identify the point of entry and point of exit, and outline the general layout of the
crime scene.
Step 3: Document
The third step in the protocol involves creating a pictorial record of the scene as well as a
rough sketch to demonstrate the layout of the crime scene and to identify the exact position of
the deceased victim or other evidence within the crime scene.
Step 4: Process
This is the last step in the protocol. The crime scene technician will process the crime scene
for evidence, both physical and testimonial evidence. It is the crime scene technicians
responsibility to identify, evaluate and collect physical evidence from the crime scene for
further analysis by a crime laboratory.
Adapted from http://www.feinc.net/cs-proc.htm
Forensic Investigators must learn to be
excellent observers
•
•
They must be able to find, document, and interpret
evidence
Observation - recognizing and noting some FACT to
gather information about the world
– You make observations using your five senses
– Observations must be specific and accurate, not
relative, so that it means the same to everyone.
• Example:
– Incorrect - the burning bag smelled
nasty
– Correct - the burning bag smelled
similar to rotten eggs
– Observations can be qualitative or
quantitative
» Qualitative observations factual descriptions that do not
use numbers
» Example: Mr. Snyder has brown
eyes
» Quantitative observations factual descriptions that do use
numbers
» Example: Mr. Snyder has two
eyes
The Power of Observation
You have thirty (30) seconds to observe the
following image and remember everything
that you can about this image. YOU MAY NOT
WRITE ANYTHING DOWN AND YOU MAY NOT
DISCUSS WHAT YOU OBSERVE WITH ANY
MEMBER OF YOUR FORENSIC TEAM
ARE YOU READY?
The Power of Observation Activity
1. What color is the truck?
2. What is the speed limit?
3. Is there a van present? What color?
4. Other than a speed limit sign, what other sign(s) are
present? What do they say?
5. Is there a sidewalk?
6. What is found alongside the nearest driveway?
7. Where is there a stop sign?
8. Are vehicles parked along the road? If so, how many?
9. How many telephone poles are there?
10. What color is the nearest sign to you?
Observation Activity #2
• Choose two members of your forensic team to be
observers and choose two people to be investigators.
• Allow the observers to look at the picture for 30
seconds. The investigators should not look at the
picture.
• After 30 seconds, the investigators should begin
questioning the observers. Each Investigator should
question each observer. Then, the Investigators
should attempt to reconstruct the scene based on
the "eyewitness testimony".
What is testimonial evidence?
Testimonial evidence includes oral or written statements given to
police as well as testimony in court by people who witnessed an
event.
Eyewitness accounts can be a useful tool in helping investigators
with analyzing a crime scene, but are not viewed to be highly
reliable. In addition, eyewitness identifications (right or wrong) can
have a big influence on the outcome of an investigation or trial.
People are likely to view the same scene in different ways
depending on their positions, line of sight, familiarity with the area,
and other factors that can interfere with a person’s ability to
remember details.
The Power of Perception
• Not always reliable
• Does not always reflect reality
Which way is the girl facing?
How many legs do you see?
Who is in this picture?
What do you see?
What do you see?
Why is perception faulty?
• Our brains can filter out or change information
• And……
The Bunny Effect video
Can you read this?
Does this image appear to be moving?
• It’s NOT!
• Just kidding, this one is
actually moving
Did you know?
According to The Innocence Project (2008)
"Eyewitness misidentification is the single greatest
cause of wrongful convictions nationwide, playing a
role in more than 75% of convictions overturned
through DNA testing." Still, the criminal justice
system profoundly relies on eyewitness identification
and testimony for investigating and prosecuting crimes
(Wells & Olson, 2003).
What factors affect a person’s memory
and their ability to identify a suspect?
Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts
Witness Factors
• Age may play a role in the accuracy of an eyewitness’ statement or
identification of a suspect. Studies have shown that when a lineup
contains the actual culprit, both young children and elderly perform well,
but when the lineup does not contain the culprit there is a higher rate of
mistaken identifications.
• The race of the witness may also play a role. The Cross Race Effect
(CRE) is a phenomenon in which people are better at recognizing faces
of their own race rather than those of other races.
• The use of drugs can alter a person’s ability to recall the events of a
crime even after they are no longer under the influence.
• A person’s memory of an event can be influenced by other witnesses,
investigators, and/or the media. Investigators use open-ended questioning
and follow procedures for conducting line-ups to limit their influence on
a witness’ memory of an event or identification of a suspect.
Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts
Crime Scene & Suspect Factors
• A crime that is extremely traumatic for an eyewitness may affect his/her
recall of the event. For example, a witness confronted with a weapon
tends to focus on the weapon rather than the perpetrator’s face.
• Someone who is able to focus on a perpetrator's face for a minute or
longer will tend to have a more accurate memory than someone who saw
the person for only a few seconds.
• Studies have shown that faces that are either highly attractive, highly
unattractive, or distinctive are more likely to be accurately recognized.
Simple disguises, such as hats or sunglasses, can interfere with accurate
eyewitness identification. However, body piercings and tattoos increases
the likelihood of an accurate identification.
• The time of day in which the crime occurred as well as a person’s view
of the scene may affect what a he/she is able to see. In addition, a person
who is familiar with the area in which the crime took place, may have a
better recall of the positions of the victims or suspects.
Source: http://www.helium.com/items/1276135-accurate-eyewitness-accounts
Crime Scene Challenge
• Now that your eyes and brain are warmed up, let’s
test your observation skills a bit more.
• You will have 2 minutes to study the photograph of a
crime scene on the next slide.
• Try to pay attention to details as you will be asked 10
questions about the crime scene!
• You are not allowed to write anything down until
after the time is up.
• Ready?
Answer each question below.
1. What color coffee mug was in the picture?
2. When was the deadline?
Yesterday
Blue
Red
Today
3. What time was on the clock on the wall?
Yellow
Tomorrow
10:40
11:05
4. How many sticky notes were on the whiteboard?
Four
Six
5. Which of the following was NOT in the picture? Stapler
6. What was the name on the plaque on the desk?
7. What color was the victim's shirt?
Black
8. How many plants were in the picture?
None
Bill
Blue
10. Where was the book in the picture? On a box
Source: http://forensics.rice.edu/html/picture_begin.html
Eight
Trash Can
Brian
Printer
Carl
Red
One
9. What was the color of the marker in the desk drawer?
1:55
Two
Red
In the trash can
Blue
Green
Under the body
Facial Composites
Investigators work with sketch artists and eyewitnesses to create
facial composites, or sketches of a person’s face. Today many
police departments are using facial reconstruction software to
help them with this task.
The composite may be used internally to assist officers in
identifying the suspect or used externally through local media
(radio, TV, and newspaper) to solicit leads from citizens.
FACES – A software program that
offers many options to help you
recreate a person’s facial features.
You will have a chance to try to create a facial composite later in
the course. You will need to pay close attention to the following
features:
The shape of the face
The shape of the jaw
The shape of the eyes
The shape of the nose
The width of the neck
The shape & protrusion of the ears
The presence of facial piercing
The presence of facial hair, its color, & location
The presence of facial markings, such as scars or tattoos
Forehead or other facial lines
The presence of eyeglasses or sunglasses
The length, color, & texture of the person’s hair
Forensic Science
This concludes an
Introduction to forensic science