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Unit 1. Forensic Science. Essential Question. What is Forensic Science?. Intro. to Forensic Science. Forensic Science – application of science to law. Essential Question. Who are some important people that have contributed to the field of forensic science?

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essential question
Essential Question
  • What is Forensic Science?
intro to forensic science
Intro. to Forensic Science
  • Forensic Science – application of science to law
essential question1
Essential Question
  • Who are some important people that have contributed to the field of forensic science?
  • What have these people contributed?
sherlock holmes
Sherlock Holmes
  • Fictional character developed by author Sir Arthur Conan Doyle
  • First to apply serology, fingerprinting, firearm identification, and questioned document examination
  • All of this – from fiction – before accepted by real-life criminal investigations.
mathieu orfila 1813
Mathieu Orfila – 1813
  • Father of Toxicology
  • Lafarge Trial (Marie) – arsenic
  • Book: Traite des poisons or Toxicologiegenerale – first scientific study of the detection and pathological effects of poisons – established toxicology as a distinct field of forensic science.
alphonse bertillon 1879
Alphonse Bertillon - 1879
  • The father of criminal identification
  • Developed anthropometry – using body length measurements as unique properties – took 243 separate measurements
  • Method was coined “Bertillonage”
francis galton
Francis Galton
  • Fingerprinting
    • Developed methodology for identification using the friction ridges on fingers
    • Basics still used today
    • His work has been enhanced by Sir Edward Henry – the father of modern fingerprinting
    • Henry developed a filing method for storing fingerprint patterns/records prior to computer storage capabilities
    • Wrote the book Fingerprints
leone lattes 1915
Leone Lattes - 1915
  • Blood testing – used technique developed by Dr. Karl Landsteiner
  • Bloodstains – developed method to determine blood type from dried blood
  • Discovered that blood typing could be used as a means of identification
calvin goddard 1920s
Calvin Goddard – 1920s

Father of Firearm Identification

  • Individualization of weapons
  • Firing pin marks on shell casings
  • Refined the technique of bullet comparison with the gun from which it was fired.
albert s osborn
Albert S. Osborn
  • Handwriting expert – established the fundamental principles of document examination.
  • Wrote Questioned Documents
hans gross
Hans Gross
  • First real life “scientific detective” – described the application of scientific disciplines to the field of criminal investigation.
  • Wrote first book on criminal investigation
  • Austrian lawyer
  • Coined the term “Criminalistics”
  • Wrote about: forensic medicine toxicology, serology, ballistics, and anthropometry
  • Suggested using: mineralogist, ecologist, and botanists
j edgar hoover
J. Edgar Hoover
  • Reorganized the Bureau of Investigations in 1924
    • Included fingerprint cards
  • 1932 now FBI
    • Organized a national laboratory that aimed to offer forensic services of all law enforcement agencies
edmond locard
Edmond Locard

Father of Forensics

  • Locard’s Exchange Principle – whenever two objects come in contact, material will be exchanged between them
  • Every criminal can be tied to crime by dust particles carried from the scene
    • Example: counterfeit coins – metal found in that matched those of the coins found on three suspects clothes – confronted with evidence – they confessed
essential question2
Essential question
  • How are crime laboratories organized in the United States?
  • What units are present in most crime labs?
  • What is the responsibility of the units in each crime lab?
  • 5 main federal labs
    • Department of Justice (DOJ) labs at the Federal Bureau of Investigation (FBI)
    • United States Secret Service (USSS)
    • Department of Treasury labs at the Drug Enforcement Administration (DEA)
    • Bureau of Alcohol, Tobacco, and Firearms (ATF)
    • Postal Inspection Services (PIS) at the U.S. Postal Service (USPS)
organization cont
Organization Cont.
  • Main lab in US is run by FBI and serves as a central repository for forensic info
  • Example
    • Integrated Fingerprinting Identification System (IAFIS)
    • Combined DNA Indexing System (CODIS)
    • Comparison standards for paint samples, tire patterns, bullets, explosives, and fibers, etc
  • Initially established to combat counterfeiting issues
  • Protected Grover Cleveland on part-time basis
  • Officially assigned to protect the president after the assassination of William McKinley
  • Maintains questioned documents lab
  • Analyze ink and paper to determine authenticity
doj lab at dea
DOJ lab at DEA
  • Analyze drugs for major components, determine side products, solvents, impurities, and starting ingredients
  • Determine geographical origin of illegal drug manufacturer
  • Allow monitoring of patterns of drug trafficking and development of illegal substances
  • Analyze physical evidence related to arson, explosives, firearms, tobacco, and alcohol
  • In conjunction with FBI developed National Integrated Ballistics Information Network (NIBIN)
pis @ usps
  • Mail crimes i.e. identify theft, mail fraud, letter bombs, child pornography
  • Can analyze envelope for location & criminal id
  • Sometimes DNA can be isolated from saliva
  • Chemistry
    • Largest unit because most evidence is drug-related and 6th amendment guarantees right to speedy trial
    • gas chromatograph-mass spectrometer for drug analysis
    • Analyze trace evidence, explosives, metals, paints, minerals
units cont
Units (Cont.)
  • Physics
    • Crime scene reconstruction (car accident)
    • Reconstruct shooting
  • Biosciences
    • Analyze biological material for DNA i.e. blood, semen, saliva, skin, hair, etc
    • Identify biological samples
  • Toxicology
    • Analyze body fluids for presence of drugs or poisons
units cont1
Units (Cont.)
  • Firearms
    • Comparison microscopy
      • Match markings left on cartridge cases by firing pin, breechblock, extractor, or ejector
      • Match test fired bullet
  • Fingerprints
    • Uncover latent prints by dusting, chemical, ultraviolet, and alternative light techniques
  • Photography
    • Record the crime scene
units cont2
Units (Cont)
  • Questioned Documents
    • Forged, altered, counterfeit documents
    • Analyze ink, handwriting, printing, erasures obliterations, and charred documents
  • Evidence Collection
    • Trained evidence collection technicians travel to crime scene
  • Evidence Submission and Holding
    • Maintain chain of custody, secure evidence
essential question3
Essential Question
  • What is the role of the forensic scientist?
  • What is the role of the crime scene investigator?
forensic scientists
Forensic Scientists
  • Main job – analyze evidence
  • Train law enforcement (CSI) to identify, collect, and preserve evidence
  • Expert witness
  • Use physical evidence to connect the crime scene, the victim, and the criminal
crime scene investigator
Crime Scene Investigator
  • Recognize, collect, preserve evidence
essential question4
Essential Question
  • What are different careers in Forensic Science?
  • Medical examiner
    • Physician authorized by state to investigate, unexpected, violent, suspicious, or unnatural deaths
  • Pathologist
    • Physician trained in determining cause of death; autopsy
  • Toxicologist
    • Detects presence of poisons or drugs in body fluids, tissues, and organs
careers cont
Careers (Cont.)
  • Odontologist
    • Forensic dentists
    • Use dental records for id especially in burn victims
  • Forensic Psychiatrist
    • Apply psychiatry to law
    • develop profile and determine competency to stand trial
careers cont1
Careers (Cont.)
  • Forensic Engineer
    • Apply engineering principle to law
    • May determine structural failure such as bridge or building collapse
  • Forensic Anthropoloist
    • Performs specialized examination of human skeletal remains or badly decomposed bodies for id purposes
  • Forensic Entomologist
    • Apply study of insects to law
essential question5
Essential Question
  • What is evidence?
  • What are the types of evidence?
  • What is the difference between individual and class evidence?
  • Something that tends to establish or disprove a fact
    • Examples
      • Documents
      • Testimony
      • Other objects
types of evidence
Types of Evidence
  • Evidence
    • Testimonial
      • Expert
      • Eyewitness
    • Physical
      • Individual
      • Class
expert witness
Expert Witness
  • Person who is a specialist in a subject
  • Only witness who can give their opinion
  • Direct witness to an event
  • Reliability
    • Scene may have been too dark
    • Encounter may have been too brief
    • Presence of a weapon may have diverted the attention of the witness
    • Memory problems
  • Individualized to a single, specific source
  • No doubt as to what the source is
    • Fingerprints
    • DNA
    • Handwriting
    • Voiceprints
  • Always involves a comparison – an exemplar
class evidence
Class Evidence
  • Consistent with a particular source
  • The more class evidence that fit the criminal – the better
    • Hair
    • Fibers
    • Soil
    • Glass fragments
circumstantial evidence
Circumstantial Evidence
  • Much evidence is circumstantial
  • Implies a fact or event without actually proving it
  • Example
    • A blond hair is found in the hand of a murder victim with black hair
  • The more circumstantial evidence the greater the probative value
essential question6
Essential Question
  • How can the probative value of class (identified) evidence be increased?
class evidence1
Class Evidence
  • Class evidence is used to narrow a suspect pool
  • The more class evidence found, the stronger the case against an individual
probability and class evidence
Probability and Class Evidence


  • A young person was seen leaving a high school parking lot after having been near a car with a broken window; the car’s CD player was missing. The suspect was identified as having light brown hair and wearing a white shirt, blue jeans, and dark-colored athletic shoes. In a school of 1600 students, how common are these characteristics?

*Note: The students do not wear uniforms.

probability and class evidence1
Probability and Class Evidence
  • Suspect:
    • White t-shirt
    • Blue jeans
    • Light brown hair
    • Dark colored athletic shoes
  • Population size = 1600
  • Sample is a typical classroom
    • Sample size = 33 students
probability and class evidence2
Probability and Class Evidence
  • In the sample, 7 students are wearing white t-shirts, so we need to find the percentage of students in the class wearing white shirts.
    • 7 wearing a white shirt divided by 33 students in class = 0.21 or 21 %
  • So, how many students is 21% of the whole population?
    • 0.21 x 1600 = 336 students
  • Importance: Our suspect pool has just been narrowed from 1600 students to 336 students.
probability and class evidence3
Probability and Class Evidence
  • How many students would be wearing blue jeans? In your class, you count 12 wearing blue jeans.
    • 12 wearing blue jeans divided by 33 students in class = 0.36, or 36%
  • How many students in the school would be expected to be wearing blue jeans?
    • 0.36 x 1600 = 576 students
probability and class evidence4
Probability and Class Evidence
  • Next, determine how many students would be likely to have light brown hair. In your class, you count 5 students with light brown hair.
    • 5 with light brown hair divided by 33 students = 0.15 or 15%
  • How many students in school would be likely to have light brown hair?
    • 0.15 x 1600 = 240 students
probability and class evidence5
Probability and Class Evidence
  • In your class, 4 students are wearing dark-colored athletic shoes.
    • 4 with dark-colored athletic shoes divided by 33 students = 0.12 or 12%
  • How many students in school would be likely to be wearing dark-colored athletic shoes?
    • 0.12 x 1600 = 190 students
probability and class evidence6
Probability and Class Evidence
  • We have narrowed the pool four times, but the real power of this method is finding the probability of a person with all of these characteristics.
  • In order to do this, multiply the probability of each event together and then by the population size.
    • 0.21 x 0.36 x 0.15 x 0.12 x 1600 = 2
probability and class evidence7
Probability and Class Evidence
  • Grand Finale
    • We have narrowed a pool of 1600 suspects down to two because we had four pieces of class evidence to consider.
    • Therefore, the probative value continues to grow by considering class evidence.
solve the following
Solve the following:
  • A teacher’s computer is stolen from C116. The culprit was wearing a purple shirt, glasses, shoes with red in them. Use the class as a sample. In a school of 1600 students, how common are these combinations of characteristics.