Introduction to Forensic

Science and Criminalistics

Prepared byPeter Bilous

Eastern Washington University

Chapter 1

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The Nature of Forensic Science

Chapter Outline 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

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What is Forensic Science?

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

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

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

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

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

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

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

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

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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: 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: Established a forensic photography laboratory

at the University of Lausanne, Switzerland in 1909

Edmond Locard: 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

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Development of Forensic Science Organizations

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

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

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:• 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

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The Scientific Method & its Application to Forensic Science

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: 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 circum-stances 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: 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:

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

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Forensic Science Specialties

Forensic Toxicology: 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

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Forensic Science Specialties

Forensic Psychiatry & Psychology: 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:• 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:

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