Transcript Forensic Science - Valhalla High School

Forensic Science
An Introduction
1. Introduction
Definition of Forensic Science
 Terms to Know
 Science Breakdown
 Founding Scientists
 Units of Forensics Labs
 Functions of a Forensic Scientist
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Forensic Science
•The
word forensic is derived from the Latin forensis,
meaning forum, a public place where, in Roman times,
senators and others debated and held judicial
proceedings.
•It
is the application of science to those criminal and
civil laws that are enforced by police agencies in a
criminal justice system.
Terms to Know:
•Algor mortis
•Livor mortis
•Rigor mortis
•Autopsy
•Expert Witness
•Locard’s Exchange Principle
What is the role of forensics?
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It is important to realize that the forensic scientist
must pull from a wide array of knowledge and
specialists to competently do his or her job.
Forensics is more of a team effort than one
would imagine. (Forget CSI, folks…….the real
world is nothing like that.)
A death that is unexpected or is thought to have
been caused by an injury or poison is always
investigated for the purpose of determining
whether or not it was a homicide.
Forensic Science
Forensic scientists use crime labs to help them examine evidence. Most
crime labs will include several departments:
physical science (including chemistry, physics, and geology)
biology
ballistics
document examination
photography
toxicology and drug analysis
fingerprints
Besides using the departments listed above, forensic crime labs may also
consult specialists in the following fields:
anthropology computer technology
voiceprint analysis
psychiatry
pathology
taphonomy
odontology
entomology
etc…
engineering
polygraphy
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Founding Scientists
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Mathieu Orfila (1787-1853)
 Father of toxicology.
 First to detect poisons in animals.
Alphonse Bertillon (1853-1914)
 Developed the science of anthropometry, the taking of body measurements
as a means of distinguishing people. (This was replaced later by
fingerprinting).
Francis Galton (1822-1911)
 First to look into fingerprinting.
 1892 wrote “Finger Prints” which talked about the science of fingerprinting.
Leone Lattes (1887-1954)
 Developed the technique for determining the blood type of a sample of dried
blood.
Calvin Goddard (1891-1955)
 First to refine the science of bullet comparison.
Albert Osborn (1858-1946)
 Authority on authenticating documents.
Walter McCrone (1916-2002)
 Perfected the use of the microscope in investigation.
Edmond Locard (1877-1966)
 Perfected the use of scientific method in today’s labs.
 Locard’s Excange Principle
Units of the Forensics Lab
Basic Units
 Optional Units
 Other Units
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Basic Forensics Units
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Physical Science Unit
 Chemistry, Physics, and Geology
 Work with drugs, glass, paint, explosives, and soil.
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Biology Unit
 Biology and Biochemistry
 Work with DNA, blood, body fluids, hair and fibers, and living organisms
(animals to plants).
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Firearms Unit
 Physics and Chemistry
 Works with gun, bullets, and trajectory plans.
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Document Examination Unit
 Physics, Chemistry, and Biology
 Works with examining handwriting, typewriting, paper and ink
documents.
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Photography Unit
 Physics and Chemistry
 Works with photos, X-ray, UV, infrared, and digital imaging.
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Optional Forensics Units
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Toxicology Unit
 Works with body fluids determining the effects of drugs and poisons.
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Latent Fingerprinting Unit
 Works solely with fingerprinting and identifying people according to
those prints.
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Polygraph Unit
 Works with validating statements made using a polygraph machine.
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Voice Printing Analysis Unit
 Works with identifying sounds and voices on recorded media.
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Evidence Collection Unit
 This unit works only with the collection of evidence from a crime scene.
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Forensic Pathology
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Tries to “get into” the criminal mind to understand why they did what they did or
what their next step will be.
Forensic Odontology
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Works with the use of insects to find the timeline of the death.
Forensic Psychiatry
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Identifies human skeletal remains. Also tries to reconstruct from the remains the
physical appearance of the deceased.
Forensic Entomology
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Works with identifying dead bodies and reason for death.
Forensic Anthropology
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Other Units
Identifies the person by their teeth or bite marks.
Forensic Engineering
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Reconstructs the crime scene.
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Methodology
The forensic scientist must be methodical
in his or her work.
 Must first observe general characteristics
of the evidence then observe more
specific features.
 Must link evidence to a crime and to the
suspects by identifying and comparing
relevant material.
 All forensic scientists use the scientific
method to conduct their investigations.
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Introduction
1. The forensic examiner must be able
to find—identify the evidence.
2. The forensic examiner must be able
to document—record the evidence.
3. The forensic examiner must be able
to interpret—accurately determine
the significance of the evidence.
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What Is Observation?
Our brains can filter out information.
Point out some of the details in this photo.
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What Is Observation?
Our brains fill in gaps in our perception.
 In order to make sense of what we perceive, our
brains often enrich with detail what we see, taste,
hear, smell, or feel.
 After an event, we can believe things were part of
the background even though they were not.
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What Is Observation?
Our brains apply previous knowledge to
new situations.
What assumptions can you make about this scene?
How might those assumptions be wrong?
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How to be a Good Observer
Observe systematically—
 Start at one part of a crime scene and run your
eyes slowly over every space.
 Slowly look at every part of a piece of evidence.
 Do not assume that later on you will be able
to remember everything.
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How to be a Good Observer
Turn off filters—
 Do not pay attention to only what you think
is important.
 On a crime scene you will not know what
will turn out to be important.
 Make a conscious effort to pay attention
to all the details in your surroundings.
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How to be a Good Observer
Leave the final interpretation of data until
later—
 Do look for patterns and make connections.
 But the more information obtained, the better will
be the interpretations.
 Remember that eyewitness accounts and
your own thinking can include prejudices.
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How to be a Good Observer
Documentation, documentation,
documentation—
 It is important to write down and photograph
as much information as possible.
 Keep in mind that memory is faulty.
 Remember that our brains tend to automatically fill in gaps in our perceptions.
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Observations in Forensics
 Study situations.
 Find clues in ordinary details.
 Work backwards from the evidence to what led
up to the crime.
 Be patient.
 Practice.
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Observations by Witnesses
are affected by:
 their emotional states.
 whether they were alone, part of a group, or
whether others were in the area.
 what type of and how much activity was going
on around them.
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Eyewitness
“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
Eyewitness
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Juries can be heavily influenced by eyewitness
accounts. But how accurate are they?
Eyewitnesses can make perceptual errors for
many reasons:
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crime scene was too dark, encounter was too brief, or
the presence of a weapon may have diverted their
attention
the stress and fear involved in witnessing a crime
may sharpen some people’s focus and confuse
others
the time between the crime and questioning
new information – viewing mug shots or being asked
leading questions
Eyewitness Accounts
 Reports from individuals about crime-scene
events often vary.
 Observations depend on the level of interest,
stress, concentration, and the amount and
kind of distractions present.
 Prejudices, personal beliefs, motives, and
any lapse in time since the occurrence can
also have an affect.
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The Innocence Project
 Barry C. Scheck and Peter J. Neufeld at the
Benjamin N. Cardozo School of Law, starting in
1992, use DNA to examine post-conviction
cases.
 The project has found that up to 87% of the
wrongful convictions they discovered were due
to faulty eyewitness identifications.
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. . . . . . . . . . . . . . . . . Summary
 The environment and our natural sensory filters
affect our ability to observe.
 Eyewitness reports can be faulty.
 Gaining good observation skills is possible.
 Forensic scientists find, document, and
accurately interpret the evidence.
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Observation Skills
 Homework for tonight: Watch NBC tonight at
either 7:30PM, 8:30PM, or 9:30PM for 5
minutes. Write down AS many observations
as you can from those 5 minutes.
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