Chapter 14: Fingerprints

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Chapter 14 Fingerprints
Fingerprints can not lie, but liars can make
fingerprints. Unknown
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Skin
Outer Layer
Boundary between Contains friction ridge
structures
Inner Layer Contains sweat glands
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Fingerprints
Sweat gland ducts extend up through the epidermis
where they release perspiration, oils, and salts.
These leave an identifiable residue conforming to
the pattern of an individuals fingerprints.
Papillae form during fetal stage of development
and remain unchaged during life.
No two prints are alike, even for identical twins.
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3 types of fingerprints

• Visible prints - prints that are visible due to
  the background or surface they are on.
• Plastic prints - those that are made by an
  impression on a material
• latent prints - invisible prints that need to be
  made visible by mechanical or chemical means

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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 characteristic ridge
  patterns that permit them to be systematically
  classified.

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Loop

• A loop must have one or more ridges entering and
  exiting from the same side. Loops must have one
  delta.
• What are the 2 bones in the forearm?
• Types
• Radialopens toward the thumb
• Ulnaropens toward the pinky (little finger)
• Which type of loop is this, if it is on the right
  hand? Left hand?

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Whorl

• Whorls have at least two deltas and a core.
• 3 Types
• Plain or Central Pocket Whorl has at least one
  ridge that makes a complete circuit.
• Double Loop Whorl is made of two loops.
• Accidental Whorl is a pattern not covered by
  other categories.

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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. They do NOT
  have type lines, deltas, or cores.
• Types
• Plain
• Tented - has a spike in the center- looks like
  its holding up a tent

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John Dillinger

• Tried to remove fingerprints with acid
• Partially successful, but enough remained for
  identification.

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Other Prints

• Earsshape, length and width
• Voiceelectronic pulses measured on a
  spectrograph
• Footsize of foot and toes friction ridges on
  the foot
• Shoescan be compared and identified by type of
  shoe, brand, size, year of purchase, and wear
  pattern.

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Other Prints

• Palmfriction ridges can be identified and
  may be used against suspects.

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Other Prints

• Footprints are taken at birth as a means of
  identification of infants.

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Other Prints

• Lipsdisplay several common patterns
• Short vertical lines
• Short horizontal lines
• Crosshatching
• Branching grooves

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Other Prints

• Teethbite 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 in the eye may be
  unique to individuals. They are used today for
  various security purposes.