The Nature of Forensic Science

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? May have, has access to, everyone? What? Everything? When? Is it determined to be? Where? Can I find it? Everywhere? How? Use your senses: sight, sound, touch, taste and smell Why? Potential to provide information to solve a crime

5. Types of Evidence Transient Evidence Odor, Temperature, Imprints and indentations, Markings, Vapor Pattern Evidence Direct Contact: Person/Object, Object/Object Conditional Evidence Light, Smoke, Fire, Location, Vehicle Status, Body Status Transfer Evidence Classification, Physical Evidence

6. 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

7. 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

8. 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.

9. 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.

10. 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

11. 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

12. 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

13. 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�

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

26. 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)

27. 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

28. 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)

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

30. 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

31. 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

32. 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

33. 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

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

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

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

37. 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

38. 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

39. 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