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  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 (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”

  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