Fingerprints

1
Fingerprints

• Forensic Science

2
Early Techniques

• Alphonse Bertillon - system of precise body
  measurements (anthropometry)
• Bertillons system rested on idea that body
  measurements never change after the age of 20
• Skeleton sizes were thought to be so diverse that
  no two people could have the same measurements.
• System included 11 measurements outstretched
  arms, head length and width, left foot length,
  left little finger length, trunk height, body
  height, width and length of right ear, length of
  the left forearm, sitting height.
• He also documented hair color, eye color, and
  skin tone.

3
Anthropometry

• For twenty years, anthropometry was thought to be
  the most accurate measurement system.
• Once police looked for a more efficient way to
  identify people, the fingerprinting system came
  through.
• Today, fingerprinting is the pillar of criminal
  identification.

4
Fingerprint Timeline

• Documentation of Chinese using FPs to sign legal
  documents as far back as 3,000 years ago
• Several years before Bertillon began work, FPs
  were used in India to bind someone to a
  contract.
• Scottish physician, Henry Fauld, published papers
  on the potential application of FPs to personal
  identification.

5
Francis Galton

• 1892- published book Finger Prints
• He discussed the anatomy of fingerprints and
  suggested techniques for recording them
• Galton also assigned fingerprint types loops,
  whorls, and arches
• His book demonstrated that no two prints are
  exactly alike
• Prints remain unchanged year after year

6
United States v. Byron C. Mitchell

• Pennsylvania-1999
• Admissibility of fingerprint evidence was
  challenged
• The defense stated that the fingerprints could
  not be proven to be unique under the current
  research.
• After 4 days of hearings, the judge upheld the
  research on fingerprints and ruled that
• Human friction ridges are unique and permanent
• Human friction ridge skin arrangements are unique
  and permanent

7
No 2 Identical Prints

• Galton calculated that there are 64 billion
  possible fingerprint combinations.
• Galtons calculations were challenged and no
  matter what formula is used there is the same
  result
• The probability for the existence of two
  identical fingerprint patterns in the worlds
  population is extremely small.
• In 90 years of research, no two prints have ever
  been identical.

8
Minutiae Points

• AKA Ridge Characteristics
• Def. The identity, number, and relative location
  of characteristics that impart individuality of a
  fingerprint
• An easier definition the ridges and valleys of a
  fingerprint
• There are as many as 150 minutiae points and
  ridges on the average print

9
Some Reality of prints

• CSI Lies to You!!!
• Former CSI from the Gadsden Police Department,
  Deanna Rice
• I have never lifted a complete print at a crime
  scene. Tell me what criminal is stupid enough to
  gingerly press their fingers on a smooth surface
  just so I can get their fingerprints

10
Anatomy of a FP
11
Unchanging Prints

• Similar friction ridges and minutiae can be found
  on the palms of the hand and on the feet.
• These skin characteristics were designed by
  nature to enhance our grip and resist slippage.
• These ridges and minutiae do not change
  throughout life.

12
Frankensteining

• Can you change your fingerprints?
• The answer is NO!!
• Your fingerprints are created during womb
  development
• You can not ever change your fingerprints
• You can damage or mutilate them, but that just
  makes you more unique

13
Skin Layers

• Outer layer of skin Epidermis
• Inner layer of skin Dermis
• Layer separating the 2 layers papillae

14
Dermal Papillae

• Your fingerprints are determined by the papillae
  layer
• In order to alter your prints you must damage
  through the first layer of skinouch!!!
• Why not just wear gloves?

15
Latent Prints

• Your skin has openings called pores that are the
  location of perspiration of sweat and body oils.
• When you make contact with a surface your body
  oils stick to a surface in the shape of your
  fingerprints.
• Prints left with this technique at a crime scene
  are called latent prints.