1. Chapter 1

2. 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

3. 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

4. Value of Forensic Science
The scientific examination of physical evidence can help to answer the following investigative and legal questions:
Who?
What?
When?
Where?

5. 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

6. 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

7. 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.

8. 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.

9. 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

10. 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

11. 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

12. 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 ( )
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”

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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)

26. 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

27. 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)

28. Forensic Science Specialties
Forensic Anthropology:
Physical Anthropology is the science of the human skeleton and how it has evolved over time

29. 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

30. 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

31. 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

32. 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

33. Forensic Science Specialties
Criminalistics:
Criminalistics involves the examination, identification, and interpretation of items of physical evidence

34. Forensic Science Specialties
Four major areas of examination:
Biological evidence
Forensic Chemistry
Pattern evidence
Other patterns (scene reconstruction)

35. Elements of Forensic Evidence Analysis
Criminalists usually specialize in one of the four areas
Recognition
Classification (identification)
Individualization
Reconstruction

36. 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

37. 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

38. 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