Download Forensic Science

Introduction to
Forensic
Science and
Criminalistics
Chapter 1
Prepared by
Peter Bilous
Eastern Washington
University
The Nature of Forensic Science
Chapter Outline
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What is Forensic Science?
Science in the Service of the Law
Value of Forensic Science
History of Forensic Science
Development of Forensic Science Laboratories
Forensic Science Professional Organizations
Nature of Science and the Scientific Method
The Application of the Scientific Method in the Forensic
Sciences
Forensic Science Specialties
Elements of Forensic Evidence Analysis
© 2007 The McGraw-Hill Companies, all rights reserved.
What is Forensic Science?
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Forensic: having to do with the law
Science: derived from the Latin
word Scientia meaning knowledge
Forensic Science: science in the
service of law
Forensic Science can be applied to
both civil and criminal cases
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Value of Forensic Science
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The scientific examination of physical
evidence can help to answer the
following investigative and legal
questions:
• Who?
• What?
• When?
• Where?
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Value of Forensic Science
Major areas of contribution include:
• Corpus Delicti
• Support or Disprove Statements
• Identify Substances or Materials
• Identify Individuals
• Provide Investigative Leads
• Establish Linkages or Exclusions
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1. Corpus Delicti
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A Latin term which refers to the “body” or
elements of a crime
The essentials facts showing that a crime has
been committed
Examples include:
• Identification of a controlled substance in a drug
possession case
• Determination of blood alcohol concentration in a
possible drunk driving case
• Identification of semen in a alleged sexual assault
case
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2. Evaluation of Statements
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The scientific examination and
analysis of physical evidence can
provide objective information by
which statements made by
witnesses, victims or suspects can be
evaluated.
The scientific findings can either
support or contradict statements
made by someone in a case.
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3. Identification of Substances
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The scientific examination of physical
evidence can provide an identification of
substances or materials.
Examples include:
• Identification of an illegal drug in a possessions
case.
• Detection of an ignitable liquid in a suspected
arson case.
• Detection of gunshot residue on the hands of a
suspect in a shooting case.
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4. Identification of Individuals
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The scientific examination of physical
evidence can provide an
identification of individuals.
Identification can be obtained
through the examination of the
following types of physical evidence:
• DNA from biological evidence
• Fingerprint impressions
• Dental information in skeletal remains
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5. Provide Investigative Leads
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Physical evidence can be helpful at the
investigative phase
A search of a database can lead to a match
with a known sample
For example:
• A forensic DNA profile comparison to samples in
the Combined DNA Indexing System (CODIS)
DNA database
• A forensic fingerprint comparison to samples in
the Automated Fingerprint Identification System
(AFIS) database
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6. Establish Linkages or Exclusions
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Physical evidence can be used to
establish a common origin or a possible
association
Evidence may connect a suspect to a
victim, suspect with a scene, or an
instrument with a victim or suspect
Similarly, physical evidence may eliminate
an individual (an exclusion or
dissociation), thus guiding an
investigation in a new direction
© 2007 The McGraw-Hill Companies, all rights reserved.
History of Forensic Science
Mathieu J. B. Orfila:
 Many forensic science specialties can be traced
back to the medicolegal institutes of Europe
 One of the most renowned medicolegalist of the
time was Mathieu Orfila (1787-1853)
 Mathieu Orfila is best known for
his involvement in the “Lafarge”
arsenic poisoning case in France
 He is often referred to as the
“father of forensic toxicology”
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History of Forensic Science
Hans Gross:
• A magistrate and law professor in
Austria
• Known for his publications and for
introducing the word “criminalistics”
• In 1893, published a Handbook for
Magistrates that greatly influenced the
practice of criminal investigations
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History of Forensic Science
Alphonse Bertillon:
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Developed an anthropometric system for human
identification in the 1890s
The limitations of this system was
shown by its inability to distinguish
between two Leavenworth, Kansas,
penitentiary prisoners, Will West &
William West
The Bertillon system was eventually
replaced by the fingerprint system
being developed by Francis Galton,
William Hershel, Edward Henry &
others in the late 1800s
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Development of Forensic Science
Laboratories
Professor R. A. Riess:
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Established a forensic photography laboratory at the
University
of Lausanne, Switzerland in
1909
Edmond Locard:
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Established one of the world’s
first police crime laboratories
in Lyon, France
in 1910
Known for the Locard Exchange
Principle
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Development of Forensic Science
Laboratories
August Vollmer:
 Established a forensic laboratory at the
Los Angeles Police Department in 1923
Colonel Calvin Goddard:
 Established a crime detection laboratory at
Chicago’s Northwestern University in 1929
 Perfected the comparison microscope for
bullet and cartridge case examinations
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Development of Forensic Science
Laboratories
J. Edgar Hoover:
 Established the Federal Bureau of
Investigation (FBI) forensic laboratory in
1932
New York City (NYC):
 The NYC Police
Department Crime
laboratory was
established in 1934
© 2007 The McGraw-Hill Companies, all rights reserved.
Development of Forensic Science
Organizations
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American Academy of Forensic
Sciences (AAFS)
Established in 1948
Approximately 5,000 members
representing all forensic science
disciplines and specialties
Started the Journal of Forensic
Sciences in 1954
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Development of Forensic Science
Organizations
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American Society of Crime Lab
Directors (ASCLD)
Established in the early 1970s
Created a Lab Accreditation
Board (ASCLD/LAB)
ASCLD/LAB began lab
accreditation in 1982
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Science & the Scientific Method
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Forensic science, is first and foremost, a
science
Scientists use a multi-step method of
inquiry known as the Scientific Method
The scientific method consists of:
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Careful observation
Conjecture/hypothesis
Testing of hypothesis (experimentation)
Confirmation or refinement of hypothesis
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Science & the Scientific Method
1. Careful Observation:
• The first step is to be observant and inquisitive
about events and phenomena in the natural
world
2. Developing a Hypothesis:
• An educated guess
• Must be an
experimentally
testable
proposition
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Science & the Scientific Method
3. Testing the Hypothesis:
• Experiments are devised to test the
hypothesis
• Experiments must be controlled
• Controlled experiments are designed to
determine the effect of one variable at a
time
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Science & the Scientific Method
4. Refining the Hypothesis:
• Hypotheses must be continuously
refined (re-tested)
• A well tested hypothesis is known as a
theory
• A well tested theory is known as a
natural law
• No hypothesis, theory, or natural law is
absolute
© 2007 The McGraw-Hill Companies, all rights reserved.
The Scientific Method & its
Application to Forensic Science
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The scientific method is an important
component of the forensic sciences
Why?
• Forensic science is a science
• Important for crime scene
reconstruction
• A logical and productive approach for
crime scene investigations
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Forensic Science Specialties
Forensic Pathology:
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Pathology is a specialty area of medicine
Pathology is the study of diseases and the bodily
changes caused by the diseases
Forensic pathologists determine the
cause of death (the medical reason
why a person died; e.g.
asphyxiation)
Forensic pathologists determine
the manner of death (the circumstances causing death; e.g. homicide)
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Forensic Science Specialties
Forensic Entomology:
• Entomology is a branch of biology devoted to
the study of insects
• Forensic entomologists use insects as
investigative aids
• By examining insects, larvae or pupae
associated with a corpse, knowing the life cycle
of insects, and by using the existing
environmental factors, forensic entomologists
can estimate the time of death
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Forensic Science Specialties
Forensic Odontology:
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Odontology is the study of the physiology,
anatomy, and pathology of teeth
Forensic odontologists perform two types
of analyses involving the human dentition
• Identify human remains by comparing
premortem and postmortem dental X-rays
• Bite mark comparisons (crime scene marks to
known bite marks)
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Forensic Science Specialties
Forensic
Anthropology:
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Physical Anthropology is the
science of the human
skeleton and how it has
evolved over time
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Forensic Science Specialties
Forensic anthropologists:
• Can determine whether found remains are
of human or animal origin
• Reconstruct the skeleton from found remains
• Provide an estimate of age, stature, and
gender
• Can sometimes determine racial origin
• Detect skeletal abnormalities and any trauma
• Can provide information about the cause of
death
© 2007 The McGraw-Hill Companies, all rights reserved.
Forensic Science Specialties
Forensic Toxicology:
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Forensic toxicology is the study of the effects of
extraneous materials such as poisons and drugs
in the body
Forensic toxicologists must determine both the
presence and the amounts of extraneous
materials in the body
Assist the medical examiners in determining the
cause of death
May be involved in the determination of ethanol
levels in blood and breath samples
© 2007 The McGraw-Hill Companies, all rights reserved.
Forensic Science Specialties
Forensic Psychiatry & Psychology:
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Psychiatry is a branch of medicine concerning the
diagnosis, treatment, and prevention of mental
illness
Psychology is the scientific study of the mind and
behavior of humans
Forensic psychiatrists & psychologists evaluate
offenders for civil and criminal competence and may
be involved in offender treatment programs
A few specialize in “profiling” of criminal cases,
primarily serial murderers and serial rapists
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Forensic Science Specialties
Forensic Engineering:
 Involved in the investigation of transportation
related accidents, material failures, and
structural failures
Forensic Computer Science:
 Use information located on computers and
other electronic devices as investigative aids
 Find hidden or deleted information to
determine if internet based crimes have been
committed
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Forensic Science Specialties
Criminalistics:
 Criminalistics involves the examination,
identification, and interpretation of items
of physical evidence
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Forensic Science Specialties
Four major areas of examination:
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Biological evidence
Forensic Chemistry
Pattern evidence
Other patterns (scene reconstruction)
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Elements of Forensic Evidence
Analysis
Criminalists usually specialize in one of the
four areas
• Recognition
• Classification (identification)
• Individualization
• Reconstruction
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Elements of Forensic Evidence
Analysis
1. Evidence Recognition:
• Recognition of physical objects as evidence or
potential evidence is the first step in a
forensic investigation
2. Classification (identification):
• Physical evidence must be classified (i.e.
identified) according to their basic
characteristics
• Classification places an object within a group
of similar objects
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Elements of Forensic Evidence
Analysis
3. Individualization:
• Individualization implies uniqueness of an item
or person among members of their class
• Individualization may result
from:
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Evidence characteristics that are
considered to be unique among
members of its class
A comparison of a questioned
item with a known item indicates
a common origin
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Elements of Forensic Evidence
Analysis
4. Reconstruction:
• The objective of reconstruction is to understand
the nature and sequence of events which created
a particular item of evidence
• The proper approach to reconstruction is to use
the scientific method
• Criminalists must make observations, develop a
working hypothesis, and thoroughly test the
hypothesis
• The hypothesis must accommodate all evidence
and information
© 2007 The McGraw-Hill Companies, all rights reserved.