FORENSIC SCIENCE Prints

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FORENSIC SCIENCEPrints
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PrintsDactyloscopy the study of fingerprints

• Making Prints
• Rolling prints
• Modus Operandi--primary identification number
• Lifting Prints
• Black, white and fluorescent powder
• Chemicals--ninhydrin, iodine, silver nitrate,
  cyanoacrylate
• Other Types of Prints
• Palm, lip, teeth, eye, ear, voice, shoe and feet
  prints

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What is a Fingerprint?

• Skin has an outer layer (epidermis) which has
  ridges projecting inward, and an inner layer
  (dermis) which has projections pressing into the
  spaces between ridges
• A fingerprint is a pattern made by the friction
  ridges, which is left behind due to sweat and oil
  that sticks to them.
• Fingerprints form during the fetal stage of
  development.

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Fundamental Principlesof Fingerprints

• A fingerprint is an individual characteristic.
• A fingerprint will remain unchanged during an
  individuals lifetime.
• Fingerprints have general characteristics ridge
  patterns that permit them to be systematically
  classified.

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Ridge Characteristics

• Minutia--lines of the fingerprint
• ridge ending
• bifurcation
• short ridge
• dot or island
• enclosure

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MINUTIA

• RIDGE ENDING

BIFURCATION
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MINUTIA

• SHORT RIDGE

DOT or ISLAND
ENCLOSURE
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Arch

• An arch has friction ridges that enter on one
  side of the finger and cross to the other side
  while rising upward in the middle.
• Types
• Plain- the arch is mild
• Tented- the arch is spiked upward

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Plain arch
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Tented arch
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Loop

• A loop must have one or more ridges entering and
  exiting from the same side it began. Loops must
  have one delta (aY pattern from diverging
  ridges)
• Types
• Radial--opens toward the thumb
• Ulnar--opens toward the pinky (little finger)
• Which type of loop is this, if on the right hand?
  Left hand?

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Whorl

• A Whorl has a minimum of 2 deltas.
• Types
• Plain- 2 symmetric deltas and a complete ridge
  circuit (circular in pattern)
• Central Pocket- 2 asymmetric deltas, one side
  appears to be stretched
• Double Loop- 2 loops and 2 deltas
• Accidental- a whorl that does not fit the 3 above
  pattern types

Plain whorl
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Central Pocket Whorl
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Double Loop (whorl)
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Accidental whorl
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Human population fingerprint distribution

• Loops 65
• Whorls 30
• Arches 5

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Primary Identification Numbers- NOTE fix this
slide in your packet
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
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Primary Identification (cont) NOTE fix this
slide in your packet
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 middle
little 16 8
4 2 1
1 1

16 8 4
2 1 1.
right 3. right 5. right 7.
left 9. left thumb middle
little index ring
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Fingers
2
8
2
1
16
8
4
1
16
4
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Latent Prints

• Latent fingerprints are those that are hidden
  and are not visible to the naked eye. These
  prints consist only of the natural secretions of
  human skin and require treatment to cause them to
  become visible.
• Most secretions come from three glands
• Eccrine--largely water with both inorganic
  (ammonia, chlorides, metal ions, phosphates) and
  organic compounds (amino acids, lactic acids,
  urea sugars)
• Apocrine--secrete cytoplasm and nuclear materials
• Sebaceous --secrete fatty or greasy substances.

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Lifting Latent Prints

• Developing a print requires chemicals that react
  with secretions that cause the print to stand
  out against its background. It may be necessary
  to attempt more than one technique, done in a
  particular order so as not to destroy the print.
• Powders--adhere to both water and fatty deposits.
  Choose a color to contrast the background.
• Iodine--fumes react with oils and fats to produce
  a temporary yellow brown reaction.

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Iodine Fingerprint
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Ninhydrin Fingerprint
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Lifting Latent Prints (cont)

• Ninhydrin--reacts with amino acids to produce a
  purple reaction.
• Silver nitrate--react with chlorides to form
  silver chloride, a material which turns gray
  when exposed to light.
• Cyanoacrylate--super glue fumes react with
  water and other fingerprint constituents to
  form a hard, whitish deposit.
• In modern labs and criminal investigations,
  lasers and alternative light sources are used to
  view latent fingerprints. It was first used by
  the FBI in 1978. Since lasers can damage the
  retina of the eye, special precautions must be
  taken and a filter used.

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Cyanoacrylate Fingerprints
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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

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Other Prints

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

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Other Prints

• Foot Prints are taken at birth as a means of
  identification for infants.

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Other Prints

• The study of lip-prints is called cheiloscopy
• 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

• The use of lip prints is not yet firmly
  established in our courts.
• Two ways to potentially use lip prints
• 1- print patterns for identification
• 2- chromatography to match lipstick marks

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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.

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Other Prints

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

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FINGEREDCrazy Criminals

• A New Jersey resident phoned police after finding
  her back door slightly ajar with a muddy palm
  print on the glass. When the officer questioned
  the woman, it was determined that she had been
  gardening. When he compared her hand with the
  lifted print, he had a match!!