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Fingerprint Patterns
The Absconder Search Unit in the Division of Parole is one of the most vital units in law enforcement. It is the primary task of the members of the A.S.U. to track down paroled felons who have stopped reporting to their parole officers. The main reason for these ex-cons fleeing parole supervision is that they have turned their backs on rehabilitation and have committed additional crimes. Identification of these absconders from justice is made exponentially easier by the computerized fingerprint system now in place in the United States and throughout the world.

Before computerization, the fingerprints of individuals had to be manually filed and then compared to all others in a particular system. In 1888, a British anthropologist by the name of Francis Galton established the first classification of fingerprints in order to hasten the retrieval process. In 1896, an English Police Official stationed in India, Sir Edward Richard Henry, revised the Galtonian system and devised a classification system based on the different patterns in the fingerprints of various individuals. The system was mainly intended for use in the identification and tracking of criminals, and its groupings are still the foundation of the fingerprint classification and storage that is employed today.

Henry's system is based on four distinct groups of patterns, with each group possessing the same basic characteristics and resemblances. Within each major group there exist sub-groups containing similar differences among patterns in that particular group. Henry‘s four types of pattern groupings (arch, loop, whorl, composite) and their interpretations are as follows:

1. Arch
In arches, the ridges of the finger run continuous from one side of the finger to the other with no recurving. There are two sub-groups that further define the arch pattern:
  1. Plain Arch---this pattern has a consistency of flow to it. It starts on one side of the finger, and then the ridge cascades upward slightly, almost resembling a wave out on the ocean. The plain arch then continues its journey along the finger to the other side. The plain arch is the simplest of the fingerprint patterns to discern.
  2. Tented Arch---this pattern is similar to the plain arch in that it starts on one side of the finger and flows out in a similar pattern to the other side. However, the difference in the tented arch lies in the ridges in the center, which are not continuous as in the case of the plain arch. The ridges, which adjoin each other in the center, converge and thrust upward, giving the impression of a pitched tent.
2. Loop
In loops, the ridges make a backward turn but do not twist. This backward turn, or loop, is differentiated by how the loop flows on the hand and not how it flows on the card on which the imprint is taken. The imprint on the fingerprint card is similar to the reverse image we see when we look in the mirror at ourselves. There are two sub-groups that Henry identified in this category:
  1. Radial Loop---these are loops that flow toward the radius bone of the hand or, in other words, when the downward slope of the loop is from the direction of the little finger toward the thumb of the hand.
  2. Ulnar Loop---these are loops that flow toward the ulna bone of the hand or, in other words, when the downward slope of the loop is from the direction of the thumb toward the little finger of the hand.
3. Whorls
In whorls, there are patterns in which there are two or more deltas (first ridge nearest the divergence point of two type lines) and there exists a recurve preceding each delta. There are four sub-groups of whorls:
  1. Plain Whorl--- in these whorls, the ridges make a turn of one complete circuit and, therefore, are circular or spiral in shape. The plain whorl is the simplest form of whorl and the most common. There are at least two deltas and a ridge whose circuit may be spiral, oval or circular in shape.
  2. Central Pocket --- in these whorls, one or more of the simple recurves of the plain whorl recurves a second time.
  3. Double Loop--- in these whorls, there are two separate loop formations. In each of these formations, there are two entirely separate and distinct sets of shoulders and deltas.
  4. Accidental Whorl--- in these whorls, the composition of the pattern is derived from two distinct types of patterns with at least two deltas. Whorls which contain ridges matching the characteristics of a particular whorl sub-grouping are classified as accidental whorls.
4. Composites
In composites, there are patterns found in fingerprints which are combinations of arch, loop and whorl. Henry subdivided the composites into four sub-groups:
  1. Central Pocket Loop---these loops recurve a second time forming a pocket within the loop.
  2. Twinned Loop---also referred to as the Double Loop, these loops consist of two separate loop formations.
  3. Lateral Pockets Loop---these loops are similar to the Twinned Loop except that their ridges bend sharply down on one side before recurving, actually forming a pocket. The F.B.I. finds it too difficult to locate these two loops, and classifies both kinds as Double Loops.
  4. Accidental Loops---these loops are a combination of any two types of pattern with the exception on the plain arch that basically has no pattern.
Today, different governing bodies may classify these patterns somewhat differently than Henry did more than a century ago. However, the original system still represents a body of work that has held up under critical review for well over a hundred years.