The individuality of any fingerprint is based not upon the general shape or pattern that it forms, but instead upon its ridge structure and specific characteristics (also known as minutiae). The recognition of these ridges, their relative number, and the approximate location of them, on the observed print, are the special characteristics that make the fingerprint a specific identifying characteristic of each individual. There are at least 150 individual ridge characteristics on the average fingerprint. If between 10 and 16 specific points of reference for any two corresponding fingerprints identically compare, a match is assumed. In a judicial proceeding, a point-by-point comparison must be graphically demonstrated for at least 12 different, but corresponding, points in order to prove the identity of a specific person. IDENTIFICATION OF PRINT CHARACTERISTICSThere are three specific classes for all Fingerprints based upon their general visual Pattern. These are: loops, whorls, and arches. Approximately 60% of the total population has loops, 35% have whorls, and 5% have arches. The three major groups are also subcategorized based upon smaller differences existing between the patterns within the specific group. These subcategories are as follows: I. ARCH II. LOOP III. WHORL a) Plain arch a) Radial loop a) Plain whorl b) Tented arch b) Ulnar loop b) Central pocket whorl c) Double loop d) Accidental whorl Examples of each of these subcategories are illustrated as follows:
Of the two types of arches, the PLAIN ARCH is the simplest of all fingerprint patterns. It is formed by ridges entering from one side of the print and existing on the opposite side. These ridges tend to rise at the center of the pattern, forming a wavelike structure. The TENTED ARCH is similar, but instead of rising smoothly at the center, there is either a sharp up thrust or spike, or the ridges meet at an angle that is less than 90 degrees. Arches do not have type lines, deltas, or cores. TYPE LINES are two diverging ridges usually coming into and splitting around an obstruction, such as a loop. A DELTA is the ridge point nearest the type line divergence. The CORE is the approximate center of the pattern. A loop must have one or more ridges entering from one side of the print, re-curving, and exiting from the same side. If a loop opens toward the little finger, it is called an ULNAR LOOP; if it opens toward the thumb, it is a RADIAL LOOP. The patterned area of any loop is surrounded by two TYPE LINES. All loops must have one delta. All whorl patterns must have type lines and a minimum of two deltas. A PLAIN WHORL and CENTRAL POCKET LOOP have at least one ridge that makes a complete circuit. This ridge may be in the form of a spiral, an oval, or any variant of a circular form. The main difference between these two patterns can be shown if an imaginary line is drawn between the two deltas contained within the two patterns. If the line touches any one of the spiral ridges the pattern is determined to be a plain whorl; if no ridge is touched, the pattern is a central pocket loop.