Forensics FINAL

  1. cains murder of able
    who was first murder
  2. 48 hours
    • homicide investigation crucial timeframe
    • chances cut in half if not solved in the time frame
  3. typical steps in a homicide investigation
    • process the crime scene
    • identifiy the victim
    • est. cause, manner, and time of death
    • ascertain a motive
    • identify suspect(s)
    • gather evidence against suspect
    • present the case to the prosecutor
  4. the crime scene
    the victim
    the suspect

    to the physical evidence
    we want to link
  5. crime scene staging
    the perpetrator purposely alters the crime scene to mislead authorities and/ or redirect the investigation
  6. Crime scene staging
    • does not include actions of family members who dress or cover a loved one
    • most common make murder appear to be suicide or accident
    • others: making the murder appear to be sex related arson to appear accidental
    • may indicate realtionship
  7. forensic pathologist
    medical doctors who investigate cause, manner, and time of death in suddenm unnatural, unexplained, or violent deaths
  8. accelerated, stopped
    Decompostition is ....... by heat, and freezing
  9. rigor mortis
    • the stiffeing of the muscles after death
    • onset 2-4 hours after death
    • disappear within 18-36 hours
    • completely gone within 48-60 hours
  10. Livor Mortis
    • the settleing of the blood in the dependent areas of the body after death
    • heart ceases to pump and gravity takes over onset in 30 mins. fixed will not blanch and will not change around 8-10 hours
  11. ocular fluid
    potassium levels in vireous humor
  12. gastrointestional tract contents
    under ordinary circumstances the stomach empties its content 4-6 hours after a meal
  13. abrasions
    removal of the superficial layers of the skin by friction of compression
  14. contusion
    brushing area of hemorrhage into soft tissue
  15. lacerations
    tear in the tissue by shearing or crushing force
  16. stab wounds
    depth exceeds the length
  17. incised wounds
    cuts, length is greater then its depth
  18. blunt force trama wounds
    • abrasions
    • contusion
    • laceration
    • fractures
  19. sharp force trauma wounds
    • stab wounds
    • incised wounds
    • chop wounds
  20. Asphyxia
    • failure of cells to receive or utilize oxygen
    • can be seen in drowning
    • inhalation of poison gases
    • suffocation
    • stangulation
  21. petechial hemorrhages
    pinpoint blood clots produced by the rupture of small vessels
  22. entrance wound
    round hole with abrasion collar smaller then other

    Image Upload 1
  23. exit whole
    Image Upload 2ragged and torn appearence generally larger then other whole
  24. tattooing
    pinpoint hemorrhages due to burned powder, unburned powder driven into skin cant be wiped off
  25. smudging/ fouling
    • from soot and smoke around wound
    • easily wiped off
    • indicates a close shot but not contact
  26. fratricide
    killing your brother
  27. 1. homicide
    2. suicide
    3. accident
    4. natural
    5. undetermined
    5 manners of death
  28. mass murder
    done in one location, targeted violence attacker selects specific target.
  29. forensic anthropology
    concerned with the identification and examination of human skeletal remains
  30. Peroxidases
    • Enzymes that accelerate the oxidation of several classes of
    • origin compounds when combined with peroxide
  31. Bloodstain + Reagent+ hydrogen peroxide=
    oxidation of thehemoglobin and a color change.
  32. Kastle Meyer color test
    phenolphthalein –color change is pink

    • Highly indicative but not specific for blood some vegetable matter will
    • lead to false positive (ex. Potatoes and horseradish
  33. 1. distilled water
    2.swab stain
    4.hydrogen peroxide color= positive result
    How to do the kestle meyer test
  34. Luminal and bluestar
    • Only when blood has been cleaned up or hidden presumptive
    • Light producing reaction called chemiluminescence emits
    • light blue color reacts with the hemoglobin
    • Need darken room captured with photography swabs collected
    • from area for potential DNA
  35. Preciptin tests
    Used to test if it is human or animal blood
  36. Semen
    • Searching for dried seminal stains
    • 1.visual
    • 2. Alternate light source (ALS) provides high intense light
    • through fibers
  37. ALS (alternative light souse)
    • Some substances fluoresces when excited by a particular
    • range of light

    • The material absorbs the exciting light and remits light at
    • longer wavelengths (stokes shift)
  38. Testing for seminal stains
    Acid phosphatase color contest (AP)

    • Acid phosphatase is an enzyme secreted by the postate glad
    • into semial fluid

    Positive=blue color 30 seconds or longer
  39. Polymerase chain reaction (PCR)
    • A technique for replicating or copying a portion of a DNA
    • strand

    Short tandem repeats (STR)

    • A region of a DNA molecule that contains short segments of
    • repeating base pairs
  40. Probability of identity
    • A measure of likelihood that two individuals selected at
    • random will have the identical STR type
  41. Mitochondrial DNA
    • DNA found outside the nucleus
    • Inherited sole from the mother

    • All individuals of the same material lineage will be
    • indistinguishable
  42. Wear gloves

    Change them often

    In between different samples

    Avoid talking, sneezing, coughing, over evidence

    Wear face masks for tough DNA

    Do not store in hot locations (trunk)

    Package in paper NEVER PLASTIC

    Air dry- if wet
    Collection of DNA
  43. Crime scene reconstruction
    • Method used to support a likely sequence of events at a
    • crime scene by the observation and evaluation of physical evidence and
    • statements made by individuals involved with incident
  44. of expectation of bias

    2.continually re-evaluate data

    3.have independent peer review
    Objectivity manner of professional detachment
  45. deductive reasoning
    • the process of drawing a conclusion based on known facts or
    • premises

    (e.g. fingerprints on table=victim touched table) concrete evidence
  46. inductive reasoning
    • the process of drawing a conclusion from the premises one
    • does not know are correct

    • (conclusion is probable but not definitive e.g. large pool
    • of blood at a scene =victim probably at scene could have transported.
  47. Faslifability
    • The ability of a theory to be disproved by being tested
    • against know information

    Seek to disprove a theory

    Look @ pleasurable alternatives
  48. 1. formulate a question
    2.father measurable observational empirical data
    3.formulate a hypothesis
    4.test hypothesis through experimentation
    5.interpret data derived from experimentation
    6.draw conclusion
    7.retest if necessary
    Scientific method
  49. trajectory
    • analyze bullet holes to determine path of the bullet and
    • determine position of victim and shooter
  50. trajectory
    the path of the bullet
  51. ballistics
    the study of a projectile in motion
  52. external ballistics
    the bullet behavior after exciting the weapon
  53. internal ballistics
    inside the gun
  54. terminal
    hit body
  55. passive
    bloodstain created without any significant outside force

    (ex. Cut, dripp. Or blood on hand touch wall)
  56. blood stain pattern analysis
    the scientific study of the size, shape, location and distribution of bloodstains in order to establish the physical events that gave rise to their origin
  57. information that can obtained from BPA
    • origin of a bloodstain
    • location or position of victim at time of bloodshed. position of suspect. movement of bleeding individuals sequence of events corroboration of witness/victim
  58. harder nonporous
    result in less spatter circular stairs at 90 degrees
  59. rough surfaces
    result in irregular shaped stains
  60. Tail points to direction blood is traveling
  61. passive
    • bloodstain created without any significant outside force
    • (ex. cut, dripp or blood on hand touch wall)
  62. spatter
    • exhibit directionality vary in size are associated with sourse of blood being subjected to an extreme force .
    • (ex. steping in blood)(gunshot)
  63. altered
    indicated the blood or pattern that has undergone a physical alternation
  64. spatter"projection mechanism, cast off pattern
    a pattern usually liner in configuration when blood is released or flung from an object in motion
  65. arterial
    • blood exiting the body under pressure from a breached artery.
    • many exhibit fluctuations EKG
    • intense red colo; oxygenated
    • downward flow pattern
  66. expirated
    blood that has been blown by the nose, mouth, or a wound in the respiratory system. often are diluted from salvia or mucus.
  67. area of convergence
    • 2D point from which the stains originated.
    • pick around 8-12 stains
    • use strings or draw lines down axis of stain.
  68. area of origin
    3D point from where the stain was projected
  69. exempler
    an authentic sample used for comparison purposes
Card Set
Forensics FINAL
Forensics final