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FORENSIC SCIENCE

FORENSIC SCIENCE. INTRODUCTION to Crime Scene Investigation . CRITICAL THINKING.

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FORENSIC SCIENCE

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  1. FORENSIC SCIENCE INTRODUCTION to Crime Scene Investigation

  2. CRITICALTHINKING When Mrs. Jackson came back from lunch, there were several messages on her desk. By changing each digit of the phone numbers to one of the three corresponding letters on the telephone buttons, can you determine from whom each message came?

  3. Answers to Critical Thinking • 336-8478 dentist • (222)686-8268 accountant • 774-6837 printer • 487-2263 husband • 247-5463 airline • 832-2437 teacher

  4. Forensic Science Definition: The application of scientific technology to supply accurate and objective information reflecting the events that occurred at a crime. What does a Forensic Scientist DO??? • Analyze physical evidence • Provide Expert Testimony • Provide training in the recognition, collection and preservation of physical evidence

  5. Complex ReasoningIn Forensic Science • Deductive (reasoning from the general to the particular) and • Inductive Reasoning (reasoning from detailed facts to general principles) • Classifying • Comparing and Contrasting • Problem Solving • Analyzing Perspectives • Constructing Support • Error Analysis

  6. Locard’s Exchange Principle • Whenever 2 objects come in contact with one another, they exchange some material (dust particles, hair, dead skin cells…) • Locard strongly believed that every criminal can be connected to a crime by dust particles carried from the scene

  7. Forensic Pathology • Investigation of sudden unnatural, unexplained or violent deaths • Answer the questions: • Who is the victim? • What are the injuries, when did they occur, and how were they produced? • 5 manners of death: natural, homicide, suicide, accident, undetermined

  8. Crime Scene Team A group of professionals investigators, each trained in a variety of special disciplines. Team Members • First Police Officer on the scene • Medics (if necessary) • Investigator(s) • Medical Examiner (if necessary) • Photographer and/or Field Evidence Technician • Lab Experts pathologist serologist DNA expert toxicologist forensic odontologist forensic anthropologist forensic psychologist forensic entomologist firearm examiner bomb and arson expert document and handwriting experts fingerprint expert

  9. First Officer at the Scene • A Assess the crime scene • D Detain the witness • A Arrest the perpetrator • P Protect the crime scene • T Take notes

  10. Eye Witness “Perception is reality.” As a result an eye witness may not be the best source of crime scene information. A police composite may be developed from the witness testimony by a computer program or forensic artist. (Eye Witness Activity) Faces Composite Program by InterQuest

  11. Spiral Grid Crime Scene Search Patterns TWO of FOUR PATTERNS

  12. Strip or Line Quadrant or Zone Crime Scene Search Patterns TWO of FOUR PATTERNS

  13. Crime SceneSketch Date: August 14, 2001 Criminalist: Ann Wilson Time: 11:35 Location: 4358 Rockledge Dr St. Louis, Mo. • A. Couch/sofa • B. Female body • C. Knife • D. Over turned Lamp • E. Chairs • F. Table • G. Fireplace E c D G A E E E F E

  14. Physical Evidence Transient Evidence--temporary; easily changed or lost; usually observed by the first officer at the scene • Odor--putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke • Temperature--of room, car hood, coffee, water in a bathtub; cadaver • Imprints and indentations--footprints; teeth marks in perishable foods; tire marks on certain surfaces • Markings

  15. Physical Evidence (cont) Pattern or Transfer Evidence--produced by direct contact between a person and an object or between two objects.

  16. Physical Evidence (cont) Conditional Evidence--produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances within a particular event. • Light--headlight; lighting conditions • Smoke--color, direction of travel, density, odor • Fire--color and direction of the flames, speed of spread, temperature and condition of fire

  17. Conditional Evidence (cont.) • Location--of injuries or wounds; of bloodstains; of the victims vehicle;of weapons or cartridge cases; of broken glass, etc. • Vehicles--doors locked or unlocked, windows opened or closed; radio off or on (station); odometer mileage • Body--position; types of wounds; rigor, livor and algor mortis • Scene--condition of furniture, doors and windows; any disturbance or signs of a struggle.

  18. Evidence Characteristics ABO Blood Typing Blood DNA Typing Class--common to a group of objects or persons Individual--can be identified with a particular person or source.

  19. Medical Examiner vs the Coroner A medical examiner is a medical doctor, usually a pathologist and is appointed by the governing body of the area. There are 7 medical examiners in the state of Missouri and 400 forensic pathologists throughout the U.S. A coroner is an elected official who usually has no special medical training. In four states the coroner is a medical doctor.

  20. Medical Examiner’s Responsibilities • Identify the deceased • Establish the time and date of death • Determine a medical cause of death--the injury or disease that resulted in the person dying • Determine the mechanism of death--the physiological reason that the person died • Classify the manner of death • Natural • Accidental • Suicide • Homicide • Undetermined • Notify the next of kin

  21. THE BODYRigor Mortis Temperature Stiffness Time Since of body of body Death • Warm • Warm • Cold • Cold • Not stiff • Stiff • Stiff • Not stiff • Not dead more than 3 hrs • Dead between 3 and 8 hrs • Dead 8 to 36 hours • Dead more than 36 hours

  22. THE BODYLivor Mortis Livor mortis is the settling of the blood, causing the skin to change colors. Lividity indicates the position of the body after death. When lividity becomes fixed, then the distribution of the lividity pattern will not change even if the body’s position is altered. Lividity usually becomes fixed between 10 and 15 hours after death.

  23. THE BODYAlgor Mortis Algor mortis is body temperature. Average human body temperature: 98.6 F (37 C)

  24. Time Frame of Death • Condition Appearance • Periphery blood drying 30 min to 2 hrs • Blue-green discoloration of skin • Right and left area of abdomen 24 hours • Entire abdomen 36 hours • Bloating 36 to 48 hours • Skin slippage 4 to7 days • Absence of smell from bones more than 1 year

  25. Time Frame of DeathEyeball Changes • Condition Appearance • Cornea drying (eyes open) minutes • Cornea drying (eyes closed) 2 hours • Corneal cloudiness (eyes open) less than 2 hours • Corneal cloudiness (eyes closed) 12 to 24 hours • Eyeball collapse more than 24 hrs

  26. THEREFORE, One can die of a massive hemorrhage (the mechanism of death) due to a fall (cause of death) as a result of being pushed (homicide), jumping (suicide), falling (accident), or not being able to tell which (undetermined). All of which are manners of death.

  27. FACETS OF GUILT • Means--the ability of have committed the crime • Motive--the reason for committing the crime. (This doesn’t have to be proven or presented in a court of law, but its what everyone wants to know.) • Opportunity--time or availability to have committed the crime.

  28. Just A Thought It’s not what you know that hurts you, its what you think you know and it’s not so . . . . .Mark Twain How does this apply to forensic science and crime investigations?

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