Fingerprinting by yaofenjin

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									Fingerprinting
   Chapter 14
          Before Fingerprints
   Before fingerprints, ID was established
    using the Bertillon system which required
    profile photographs as well as precise
    body measurements called anthropometry.
    Eleven measurements were used in the
    belief that no two individuals would have
    the same measurements
                 Henry Fauld
   First to suggest the application of
    fingerprints to identification particularly in
    the criminal justice system in 1880. His
    system was rejected in favor of the
    Bertillon system.
             Francis Galton
   Provided much needed research on
    fingerprints
   Divided them into loops, arches, and
    whorls
   He successfully demonstrated that no two
    prints were the same and that prints
    remain consistent through life.
             Sir Edward Henry
    In 1897 developed the fingerprint
    classification system that is still used in
    most English-speaking countries.
          Fingerprinting History
   The first official use of fingerprinting in the US
    was in 1901 as a way of certifying civil servants.
   In 1999 in the US v. Mitchell, the admissibility of
    fingerprints was challenged. The defense argued
    that under Daubert, fingerprints could not be
    proven to be unique. After 4 days, the judge
    reaffirmed the admissibility of fingerprints.
                   Fingerprints
   One of the oldest and most important
    pieces of physical evidence.
   Based on highly individual friction ridge
    patterns on the end joints of the fingers
   Member of the pattern group of evidence
   Have individual characteristics
       Can be attributed to a single source (ideally)
     Fingerprints as Identification
   Can be used to locate, identify, and
    eliminate suspects
   Can be used to identify remains
   Biometric identifiers for security
        Fundamental Principles of
             Fingerprints
   Every fingerprint is unique to an individual
   Fingerprints do not change throughout life
    unless damage has occurred to the dermal
    skin layer
   Fingerprints have general ridge patterns
    that allow them to be classified.
         What are fingerprints?
   Complicated system of hills and valleys
    (ridges and furrows)
   Develop during early embryonic
    development and remain constant
    throughout life.
   Has a genetic factor but identical twins
    have distinguishably different fingerprints
                         Minutiae
   Also called ridge characteristics
   Used to compare fingerprints and determine
    whether or not they are from the same
    individual.
   If 2 prints are to compare they must:
       Reveal characteristics that are identical
       Characteristics must be in the same relative location
   Ridges can:
       End abruptly (ending ridge)
       Splitting into 2 ridges (bifurcation)
       Being short in length (dot)
Bifurcation   Ridge Ending




 Dot
            Identical features
   8-16 identical features are needed to
    confirm a match to a comparison sample.
   There is no established minimum to
    consider a print a match.
                 Basic Patterns
   Arch (around 5%)
       Plain or tented
   Loop (around 60%)
       Radial or ulnar
   Whorl (around 35 percent)
       Plain, central pocket loop, double loop,
        accidental
                         Loops
   Must have at least one ridge that enters,
    recurves, and exits from the same side
       If loop opens towards little finger then it is an
        ulnar loop
       If the loop opens towards the thumb it is a
        radial loop
   All loops must have a delta
                    Loops
   Left-leaning (ulnar) Right-leaning (radial)
                    Arches
   Ridges enter from one side and leave from
    the other
   Arches have no deltas or cores
   Tendency to rise slightly in the center
   If the rise is gradual then it is a plain arch
   If the rise is abrupt then it is a tented arch
            Arches
   Plain            Tented
                         Whorls
   All must have type lines (2 diverging
    ridges) and at least 2 deltas.
   Plain and central pocket loops must have
    at least one ridge that makes a complete
    circuit.
       If an imaginary line is drawn between the 2
        deltas and it touches any of the spiral ridges
        then it is plain whorl if not then it is a central
        pocket loop
                   Whorls
   Double loop—two loops in any one
    fingerprint
   Accidental—contains 2 or more patterns or
    is not a pattern covered by other
    catergories
              Whorls
   Whorl   Double loop   Double loop
                          with central pocket
                Henry System
   A modified version of the original Henry system.
   Consists of a ten print system (fingerprint card)
   Downfall is that system requires all 10 prints
    while typical evidence is a single or even partial
    print.
   While it is possible to compare this single prints
    with the cards you would need to have a
    particular suspect in mind.
           Primary classification
   (R. index/R. thumb) (R. Ring/ R. Middle) (L.
    Thumb/R. Little) (L. Middle/ L. Index) (L. little/
    L. Ring)
   Based on the presence or absence of a whorl
   If a whorl is on the 1st pair it is worth 16, the 2nd
    pair—8, 3rd pair—4, 4th pair—2, 5th pair—1
   If a arch or loop is present then it is awarded a
    value of 0
   Values are totaled and a 1 is added to both the
    denominator and the numerator
           Primary Identification
                Numbers
Fingers are numbers 1 through 10 starting with the thumb on the
right hand and continuing through with the thumb on left hand.
Each finger is then given a point value as seen in the chart below.


 1. right     2. right    3. right     4. right     5. right
    thumb         index      middle        ring        little
      16          16          8           8            4

 6. left      7. left     8. left      9. left    10. left
    thumb         index       middle       ring      little
      4            2          2           1           1         27
Primary Identification (cont)

Set up a ratio of even numbered fingers over odd numbered,
adding one in both the numerator and denominator.

 2. right    4. right   6. left      8. left   10. left
    index       ring       thumb        ring       little

      16          8           4          2            1
                                                                 1
                                                             +
     16           8           4          2            1          1

  1. right   3. right   5. right     7. left   9. left
     thumb       middle     little       index     little
                                                            28
                Fingers


        2   2                  8
    1                     16       8
1                                      4
                     16
                4




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               Classification
   Is used for classification and to provide
    officers with a number of possible
    matches
    Computer-based Fingerprints
   Development began in 1960’s
   AFIS
       Automated fingerprint identification system
   By 1990, most all large jurisdictions had a
    system in place.
   Has a 15-20 % hit rate
   Still requires a scientists to make a
    positive ID.
                        AFIS
   2 applications
       Scan for a match with 10-print sets taken
        from an individual (known sources)
       Scans for matches with prints taken at crime
        scenes (whether source is known or not)
   Problems:
       Systems don’t always correspond. Prints could
        be in one system and not another.
                       AFIS
   Once an individual is arrested; their prints
    are entered into the system
   IAFIS recently became available
       National criminal database
       15% of prints entered match immediately
                 Types of prints
   Patent (visible)
       Needs no processing to be recognizable as a
        print. Often from grease, blood, oil, or dirt
   Plastic
       Impression; recognizable fingerprint in a soft
        receiving material such as butter, putty, or tar
   Latent
       Requires additional processing in order to
        visible and suitable for comparison
                   Latent Prints
   The basis for a latent print is a watery or
    oily form of sweat residue
   Developing latent prints depend on
    residue composition
   Methods can be:
       Physical
       Chemical
       Special illumination
                    RUVIS
   Reflected Ultraviolet Imaging System
   Can locate prints on nonabsorbant
    materials without the use of chemicals or
    powders
   Detects the print in its natural state by
    using UV light. UV light is then reflected
    and converted into visible light using an
    image intensifier
              Physical Methods
   Brush and powder combined with a tape
    lift
   Magna Brush
       Uses a magnet versus a brush
   SPR (small particle reagent)
       Most commonly used on wet evidence
       Applied by spraying or immersion
              Chemical Methods
   Iodine fuming
       Must be photographed quickly because the
        color fades quickly. Can be used for valuable
        items because it is nonpermanent
   Ninhydrin
       Reacts with amino acids components of
        fingerprints to develop bluish-purple prints
       Had to be modified due to ozone restrictions
              Chemical Methods
   Cyanoacrylate (super glue)
       Excellent method that yields a stable, robust
        impression in an off-white color
   PD
       Silver nitrate compound
       Often used as a back-up
          Illumination Methods
   Alternating the light source can make
    prints visible. They can then be
    photographed for comparison.
            Preservation of Prints
   Should be photographed and then:
       If the object is small, it should be transported
        to the crime lab
       If the object is too large or permanent then it
        must be lifted.
          Digital Enhancement
   Fingerprints can be digitally enhanced
    using digital imaging software
                   Other Prints
   Ears--shape, length and width
   Face--pictures being used in Florida to find
    criminals
   Voice--electronic pulses measured on a
    spectrograph
   Feet--size of foot and toes; lines of the feet
   Shoes--can be compared and identified by
    type of shoe, brand, size and year of
    purchase                                         44
Other Prints



     Palm--lines can be
       identified and may
       be used against
       suspects.




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                  Other Prints

Lips--display one of
  five common
  patterns
     Short vertical lines
     Long vertical lines
     Rectangular lines
      that may crisscross
     Diamond
     Branching


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Other Prints

      Teeth--bite marks
        are unique and
        can be used to
        identify suspects.
        These imprints
        were placed in
        gum and could be
        matched to crime
        scene evidence.
                             47
Other Prints

     The blood vessel
       patterns may be
       unique to
       individuals. They
       are used for today
       various security
       purposes.


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