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Fingerprint Evidence and Analysis, Friction Ridge Skin, Collection and…

- - - - Sweat glands
        
        Secrete sweat that leave latent prints
        
        Developed through
- - - - And it's reliability
- - - - Transferred to
        
        Lifting cards/backing sheets
        
        Used to
        
        Document prints
        
        Enhance prints
        
        Proper packaging!
        
        Maintains
        
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- - - - Level 3 detail praints
  - - - False negatives
      - Inconclusive evaluations
- - - - insufficient detail for ACE-V
        
        Leading to errors
- - - - Cyanoacrylate fuming (superglue)
        
        It can
        
        Create white polymer on ridges
      - chemicals, powders and light
        
        Chemical reagents
        
        Used on
        
        Porous surfaces that have potentially absorbed prints (paper, cardboard, stone, etc)
        
        Surface type
        
        Can influence
        
        1 more item...
        
        Examples include
        
        physical developer, DFO, ninhydrin
        
        Alternate Light Source (ALS)
        
        Visualizes
        
        Near to invisible fingerprints
        
        Powder dusting
        
        Used on
        
        Nonporous surfaces (that do not allow any substance to pass through)
        
        adheres to
        
        sweat and oil residue
    - - Caused by
        
        sweat and oils
        
        Cause latent prints to be detectable at all
  - - - Formed in soft butter, clay, wax, etc
  - - - Made from blood, paint, ink, etc
- - - - And stable in similar contexts
  - - - Independent of context
- - - - 3% false positives
      - 0.16% false positives
  - - - 7.5% false negatives
- - - - Case shows that fingerprinting analysis is not always accurate, or flawless
- - - - Examine the examiner's accuracy without analyzing their reasoning
      - Use blind sample prints
      - Produce error rate estimates
- - - - Black-box studies!
- - - - Evaluation
        
        Inconclusive Evaluation
        
        Detail is not enough or insufficient
        
        True inconclusive
        
        Examiner correctly identifies that no conclusion about identification can be made
        
        False inconclusive
        
        Examiner incorrectly identifies that no conclusion about identification can be made.
        
        Exclusion Evaluation
        
        Differences cannot be explained
        
        True exclusion
        
        Examiner correctly identifies the prints are not from the source
        
        False exclusion
        
        Examiner incorrectly identifies the prints are from the source
        
        Verification
        
        Additional review of another forensic examiner
        
        Can reduce
        
        False positives
        
        Identification Evaluation
        
        Enough agreement of details
        
        Odds higher of likelihood with Level 3 clear prints
        
        True Identification
        
        Examiner correctly identifies the prints are from the source
        
        False Identification
        
        Examiner incorrectly identifies prints are not from the source
        
        Can be subject to
        
        Confirmation bias
        
        Can influence the examiner's conclusion
      - Unknown print to known print
      - Ridges
        
        Level 2 Minutae
      - Agreement or disagreement of ridge details
    - - The suitability of print
      - Levels of Detail (Levels 1-3)
      - Quality of collection
    - - print development quality
        
        Poor development
        
        Increase
    - - And analysis quality can affect false negative likelihood
- - - - Minutae
        
        Include ridge endings, bifurcations, islands
        
        Which individualizes prints
        
        More unique ridges can support
        
        Identification evaluation
        
        Formed by
        
        Friction ridge structure
        
        Connected to
        
        Lower quality minutae prints
        
        Increase inconclusive and misidentifications
        
        Integrity of minutae
        
        depends on
        
        ridge fidelity (biological quality)
    - - Confidence in correct identification
    - - Comparison
  - - - Overall ridge flow
        
        And pattern type!
        
        Helps with initial classification in analysis!
  - - - Ridge edge shapes and pores
    - - Clear, high quality prints
        
        Reduces
    - - Support any more identification
- - - - ridges enter one side and exit the other
        
        Lack
        
        Deltas and cores
        
        Deltas and cores are focal points for reference for classification
        
        Orientation (core/delta positions) support
        
        Evaluation of sufficient agreement
      - Least common of all
    - - Ridges are spiral
        
        Have two deltas and one core
      - Less common than loops
    - - Ridges enter and exit the same side
        
        Have ONE delta
        
        Classified as
        
        Ulnar (towards pinky)
        
        Radial (towards thumb)
      - Most common
    - - Depend on ridges and furrows of friction ridge skin