forensics midterm part 2

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forensics midterm part 2
2010-10-11 12:37:00
part midterm

midterm part 2
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  1. Shutter speed
    • the length of time that the film/microchip is exposed to light
    • fractions of a second vs 1 second
  2. bulb setting
    shutter stays open as long as you want it open
  3. depth of field
    the amount of area in the foreground and background of an object in focus smaller aperture (F/22)-=greater depth of field in focus
  4. flashes
    • supplies artificial light
    • 1. direct
    • 2. bounce
    • 3. oblique < 45 degrees show greater detail with shadowing
  5. filters
    helps to enhance specific elements of the picture by allowing certain wavelengths to reach the film
  6. 1. overall
    2. medium
    3. close-up
    3 types of photographs
  7. overall photographs
    • exterior of residence car
    • door windows
    • general terrain
    • rooms- over lap and shoot from 4 corners to get a full view
  8. Medium
    • evidence establishing shots
    • a piece of evidence is framed with some obvious landmark located in an over shot
    • gives viewer an idea of where the item is located
  9. close-up
    photo goal is to provide detail identifying marks, shape (need scale)
  10. video
    • adds to photographs not replacement
    • great for them at the scene
    • move slowly
    • turn off microphone
  11. Crime scene sketch
    • serves as a grapher representation of the scene showing layout orientation and relationships
    • 1. rough
    • 2. finished
    • hand drawn with rules
    • computer aided
  12. sketch
    • include location of doors, windows, furniture, victims, evidence and any important items
    • dimensions of rooms
    • need title block
    • victims name , date, address location, name of artist case #
  13. Birds- eye view
    only horizontal surfaces are represented
  14. exploded view
    same as birds eye view but the walls are collapsed good for evidence located on walls
  15. 3D view
    view done with computer
  16. Crime Scene mapping
    defines the size of the scene and where in the scene items are located
  17. 1. rectangular coordinated
    2. triangular
    3. baseline
    4. polar coordinates
    5. total station mapping
    5 measuring methods
  18. rectangular coordinates
    two distances to an object at right angles
  19. triangular
    measure the distance to an object from fixed points
  20. baseline
    • measuring tape from two fixed spots and then second measurement at 90 degrees
    • used in accidents
  21. polar coordinates
    one reference point is used with distance and direction (angle) using a compass
  22. total station mapping
    electronic device that measures distances, angles, and heights
  23. collect evidence
    perform additional processing techniques once evidence is removed
    things that could damage evidence
    Final steps at the scene
  24. physical evidence
    • any object that can establish a crime has been committed or that can link a crime and its victims or perpetrator
    • must recognize it
    • collect it properly
    • package it correctly
  25. contamination
    • the transfer of extraneous matter between the collector and the evidence
    • eg tracking in fibers from your house
  26. cross-contamination
    the transfer of matter between two or more pieces of evidence
  27. chain of custody
    a list of all people who came into possession of an item of evidence
  28. standard/reference
    physical evidence whose origins is known, such as blood or hair from a suspect that can be compared to crime-scene evidence
  29. collected=>crime lab=>document=>analyzed =>report written
    submitting evidence procedure
  30. identification
    the process of determining a substance physical or chemical identity (e.g. cocaine, TNT, blood, seman, species)
  31. process of identification
    • adoption of testing procedure
    • number and type of tests much be sufficient to exclude all other substances
  32. comparison
    • the process of acertaing whether two or more objects have a common origin
    • suspect specimen vs. standard/reference specimen ( paint chip from hit and run compared to paint from suspects vehicle
  33. Process of comparison
    • combination of select properties are chosen from each and reviewed
    • the examiner draws a conclusion about the origins of the speciemans
    • do they or do they not come from the same sourse?
    • if one or more properties is different =not the same sourse
    • based on education and training.
  34. physical evidence
    individual characheristics properties of evidence that can be attributed to common sourse with an extremely high degree of certaninty
  35. ridge characterists of fingerprints
    striations on a bullet
    wear patterns on footwear
    break matches
    example of physical evidence
  36. class charactoristics
    properties of evidence that can only be associated only with a group and not a single sourse
  37. single layer automobile paint chip
    foot wear/ tire without indiviual marks
    Hair (without DNA potential)
    can only be good circumstanial evidence
    examples of CLASS charactoristics
  38. evidence
    anything that tends to prove or disprove a fact of the case at trial
  39. direct evidence
    evidence that directly proves a fact without any inference or presumption
  40. circumstantial evidence
    • evidence gained from deductions made from related facts and circumstances indirect evidence
    • Real, testimonal and relevant (probative)
  41. its ability to corroborate events with data in a manner that is (as nearly as possible) free of human error and bias
    The most important value of physical evidence
  42. Automated Fingerprint identification (AFIS)
    • computer database with finderprints
    • converts scanned images of fingerprint into digital minute
    • once a list is produced it is up to a trained examiner to match the print
  43. Combined DNA index system (CODIS)
    • computer stores DNA profiles from around the country
    • local state and national labs house profiles are interconnected
    • all 50 states
    • FBI houses national data and includes US army and puerto rico