Fingerprints

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Fingerprints

• 90 of the information in this presentation was
  taken directly from
• http//www.brazoria-county.com/sheriff/id/fingerpr
  ints/index.htm

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Ancient History is a mystery

• Suggested that thumbprints on Babylonian clay
  tablets and ancient Chinese clay seals were
  deliberately placed there as identifying marks

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Sir Francis Galton

• Established that fingerprints are unique.
• Wrote book Fingerprints
• This introduced modern techniques of criminal
  investigation, replacing tatooting, branding, and
  body measurements as methods of identifying
  criminals.

(Charles Darwins Cousin)
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Galtons Premises(or Galton Details)

• First to categorize minutia and observe that they
  remain unchanged.
• Uniqueness
• All Fingerprints are different
• Nature does not repeat any object in complete
  detail.
• Permanence
• Fingerprint patterns remain constant as a person
  matures.
• Superficial skin damage grows back to original
• Severe cuts and resulting scars remain permanent.

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Sir Edward Richard Henry

• Developed a method of indexing fingerprints
  Henry Classification System.
• Problem need all 10 prints
• Book Classification and Uses of Fingerprints
• Classifies fingerprints into three types Arches,
  Loops, and Whorls

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Johannes Purkinje

• In his doctoral thesis, he identified nine print
  patterns
• Arch
• Tented arch
• Loop
• Six Whorls

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The basic tenets of friction skin identification
areFriction skin is UNIQUEFriction skin
develops before birth, is PERMANENT and NEVER
CHANGESVariation in ridge patterns vary within
specific limits and can be classified.
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ACE-V

• Analysis
• Comparison
• Evaluation
• Verification

The generally accepted method for friction
ridge individualization
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RIDGE Detail
1st Level Detail
2nd Level Detail

3rd Level Detail
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Where to look for minutiae

• The area immediately surrounding a delta will
  probably contain more points per square
  millimeter than the area near the tip of the
  finger which tends to not have that many points.

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Finding Minutiae

• These are only 10 of the 22 in this ¼ X ¼ inch
  section.

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Finding Minutiae

• May not be all that easy. In real life,
  impressions
• are made at separate times.
• are subject to different pressure distortions.
• from a crime scene are anything but clear.
• from a crime scene could be a fingertip, palm or
  even foot impression, not the core of a
  fingerprint.

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Classification

• Ya gotta be able to find the delta(s) or
  recognize a lack of them!
• Deltas
• a place where two lines run side-by-side and
  then diverge with a significant recurving line
  that passes in front of the delta.

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Classification Based on Deltas

• If the print has one delta then the pattern is a
  loop.
• If the pattern has more than 1 delta then it is a
  whorl.
• If the pattern has no delta's then it is an arch.

Simple enough so long as you can effectively
identify the deltas.
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Classification Loops (65)
Loops only have one delta. They also have one
core.
Core
Delta
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Arm Bones

• Radius on thumb side thick near wrist

Ulna
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Ulnar and Radial Loops

• If on left hand, comes in and goes out from
  pinky side ulnar side
• ulnar loop

If on right hand, comes in and goes out from
thumb side radial side radial
loop
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Plain Arch

• No delta
• No significant core

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Tented Arch

• Has a "significant upthrust"
• No, thats not a delta. To be a valid delta there
  has to be a significant recurving line that
  passes in front of the delta

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Plain Whorl

• Must be more than one delta
• Must intersect lines that make up the whorl when
  you draw a straight line between the deltas.

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Are these plain whorls?
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Central Pocket Whorl

• The ridges that form the inner pattern of the
  whorl are not crossed by an imaginary line drawn
  between the two deltas.

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Accidental Whorl

• Is a pattern not covered by other categories, or
  is a combination (e.g., loop and plain whorl or
  loop and tented arch).

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Double Loop Whorl

• Has two separate and distinct loop formations
  with two separate and distinct shoulders and two
  deltas

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Double Loop Whorl

• The shoulders of each "core" must comprise
  separate lines.

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Double Loop Whorl

• The shoulders of each "core" must comprise
  separate lines.
• Here they dont.