Fingerprint Patterns

1
Fingerprint Patterns

• You be the detective!

2
The Basics

• A fingerprint is an impression of the friction
  ridges of all or any part of the finger.
• A friction ridge is a raised portion of the
  epidermis on the palm and fingers or sole and
  toes skin, consisting of one or more connected
  ridge units of friction ridge skin.
• These ridges are sometimes known as "dermal
  ridges" or "dermal papillae".

3
Print Facts

• Fingerprints may be deposited in natural
  secretions from the glands present in friction
  ridge skin (secretions consisting primarily of
  water)
• They may be made by ink or other contaminants
  transferred from the peaks of friction skin
  ridges to a relatively smooth surface such as a
  fingerprint card.

4
Reliability of fingerprinting as an
identification method

• Fingerprints collected at a crime scene, or on
  items of evidence from a crime, can be used in
  forensic science to identify suspects, victims
  and other persons who touched a surface.
• No two fingerprints have ever been found
  identical in many billions of human and automated
  computer comparisons.
• Fingerprints are the very basis for criminal
  history foundation at every police agency.

5
Fingerprints old school?

• Is claimed to outperform DNA and all other human
  identification systems to identify more
  murderers, rapists and other serious offenders
  (fingerprints are said to solve ten times more
  unknown suspect cases than DNA in most
  jurisdictions).

6
Print History

• The discovery of fingerprints has been widely
  attributed to a 19th century scientist named
  Francis Galton.
• An ancient Chinese custom includes using the
  fingerprint to sign legal documents .

7

• Galton's proposal that "no two fingerprints are
  identical" changed the world of forensic science
  forever.
• In order for fingerprinting to be useful in
  forensic identification, a method of sorting and
  classifying them would be necessary.

8
Fingerprint Locks

• In the 2000s, electronic fingerprint readers were
  introduced for security applications such as
  identification of computer users (log-in
  authentication).
• However, early devices have been discovered to be
  vulnerable to quite simple methods of deception,
  such as fake fingerprints cast in gels.
• In 2006, fingerprint sensors gained popularity in
  the notebook PC market. Built-in sensors in
  ThinkPads, and others also double as motion
  detectors for document scrolling, like the scroll
  wheel.

9
Types of Prints

• Fingerprint impressions fall into three basic
  types latent, visible, and the plastic (molded),
  prints.
• Latent print invisible to the eye.
• Latent prints are formed by sweat
• Even the swiftest of criminals find it difficult
  to escape without leaving behind the trace of a
  single fingerprint.

10
Types of Prints Continued

• Fingers stained with blood or ink found can form
  visible prints.
• Plastic prints are quite easy to read because
  they make an impression on a soft surface such as
  soap, putty, or wax.

11
LOOPS

• Loops constitute between 60 and 70 per cent of
  the patterns
• One or more of the ridges enters on either side
  of the impression, recurves, touches or crosses
  the line of the glass running from the delta to
  the core

12
RADIAL/ULNAR LOOPS

• Depends on the way the loop travels
• Obviously to make the distinction between these
  two types of loops you have to know on which hand
  they appear

13
WHORLS

• Any fingerprint pattern which contains 2 or more
  delta's will be a whorl pattern.

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Types of Whorls
A
O
S
CENTRAL DOUBLE LOOP
ACCIDENTAL POCKET
15
CENTRAL POCKET  WHORLS

• Notice the inner area of the pattern, that is the
  area which tends to form a circle?

16
DOUBLE LOOP  WHORLS

• Looks like a ying yang symbol in the centre of
  the whorl

17
ARCHES

• Arches represent only about 5 per cent of the
  fingerprint patterns encountered. In arch
  patterns, the ridges run from one side to the
  other of the pattern, making no backward turn.
  There is ordinarily no delta.

18
COMPOSITES

• Composites include patterns in which combinations
  of the tented arch, loop and whorl are found in
  the same print, also patterns where the majority
  of ridges are loops and a few ridges at the
  centre or side are whorls. These are subdivided
  into central pocket loops, double loops and
  accidentals.

19
Superhero Thumbprints

• At the back of the lab there are ink pads and
  worksheets.
• You are to ink both your right and left thumbs
  and then put them in the appropriate boxes.
• Put a star beside any deltas
• that you see
• Identify the pattern of your
• thumbprint.
• Pass into Ms. Clarke and get an
• exit card to complete by the end
• of class.