Fingerprint Patterns and Identification

FINGERPRINTS

PATTERNS

• LOOPS
• WHORLS
• ARCHES
• TEST QUESTION: Be able to look at a pattern and identify it as a loop, whorl, or arch.

LOOP

• The ridges enter on one side of the pattern, recurve back, and exit the same side they entered.
• Two types of loops:
  • Ulnar
  • Radial (named after bones in the arm)
• Loops are also described as right slant or left slant, depending on the direction they flow out.

WHORL

• Whorls have 2 deltas.
• A recurving ridge exists in front of each delta.
• Types of whorls:
  • Plain whorl
  • Central pocket loop whorl
  • Double loop whorl
  • Accidental whorl

ARCHES

• TWO TYPES: Plain and Tented
• Plain arch: A pattern in which the ridges enter upon one side, make a rise or wave in the center, and flow out the opposite side.
• Tented arch: A pattern in which the ridges enter upon one side and make an up thrust or angle in the middle.

DELTA

• The delta is that point on a ridge at or nearest to the point of divergence of two type lines, and located at or directly in front of the point of divergence.
• Deltas are the lines that go around the pattern in the fingerprint; one goes up, and one goes around it at the bottom.
• TEST QUESTION: Be able to pick out the delta on a fingerprint.

CORE

• The core is the approximate center of the pattern.
• Test Question: Core

HOW TO COMPARE

• We use minutiae, which are points of similarity.
• test question

Fingerprint Minutiae

• Features inside fingerprint patterns based on how the ridges form.
  • ridge ending
  • bifurcation
  • bridge
  • crossover
  • core
  • dot
  • island
  • hook (spur)
  • lake
  • bifurcation
  • ridge ending
  • island
  • delta
  • pore