Chapter 4: Fingerprints. History. First fingerprints were discovered in clay pottery during the T’ang Dynasty Dactyloscopy : study of fingerprints. FINGERPRINTS. History. Alphonse Bertillion First systematic attempt at personal identification Bertillion system
Every fingerprint is unique!
A fingerprint is a pattern comprised of ridges and valleys.
A Ridge – is a high.
A Valley – is a depression or low.
Friction ridges are also found on our palms, feet and toes.
Figure4.3 Loop pattern.
How are fingerprints compared?
Fingerprints are compared by noting the ridge characteristics on two prints to determine whether or not they match.
An identification is established when a number of these characteristics occupy the same relative position on the two prints.
Fingerprints and a fingerprint classification schema involving six categories: (a) arch, (b) tented arch, (c) right loop, (d) left loop, (e) whorl, and (f) double loop. Critical points in a fingerprint,called core and delta, are marked as squares and triangles.
Eye or Enclosure
Row of Dots
RIDGE CHARACTERISTICS (Minutiae)
Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!
RIDGE CHARACTERISTICS MAGNIFIED
Points 1, 2, 4, 5 are Ending Ridges
Points 3 and 9 are Dots
Points 8, 10, 11 are Bifurcations
Point 6 is an Enclosure
Point 7 Short Ridge
Spike or “tent”
Ridges enter on one side and
exit on the other side.
Similar to the plain arch,
but has a spike in the center.
Arches are the simplest type of fingerprints that are formed by ridges that enter on one side of the print and exit on the other. No deltas are present.
Loops must have one delta and one or more ridges that enter and leave on the same side. These patterns are named for their positions related to the radius and ulna bones.
Ulnar Loop (Right Thumb)
Loop opens toward right or the ulna bone.
Radial Loop (Right Thumb)
Loop opens toward the left or the radial bone.
NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop.
Whorls have at least one ridge that makes (or tends to make) a complete circuit. They also have at least two deltas. If a print has more than two deltas, it is most likely an accidental.
Central Pocket Whorl
Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl.
Double Loop Whorl
Double loop whorls are made up of any two loops combined into one print.
Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories.
Types of PrintsVisible & Latent Prints
Visualizing Latent Prints
*converts to dark Ag2O
Super Glue fuming
** can be enhanced,
compared and sent to
AFIS within minutes.
AFIS can compare hundreds of thousands of
prints in less than a second.