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# Fingerprint Patterns and Ridge Characteristics

There are three main types of fingerprint patterns with several subgroups of patterns:

1. Arch patterns account for approximately 5-15 percent of fingerprint patterns. Arch patterns can be further categorized into two subgroups:

a. Plain arches

b. Tented arches

2. Loop patterns account for 60-65 percent of fingerprint patterns. The loop pattern is the most common. There are two subgroups (automated systems simply use the terms right slant or left slant):

a. Ulnar (ridges flow toward the little finger)

b. Radial (ridges flow toward the thumb)

3. Whorl patterns account for 30-35 percent of fingerprint patterns. Whorls can further be categorized into four subgroups:

a. Plain

b. Double loop—sometimes called lateral loops

c. Central pocket loop

d. Accidental

Ridge characteristics or Galton details may take the following forms:

• 1. Staple or recurve
• 2. Convergence
• 3. Appendage
• 4. Bifurcation
• 5. Divergence
• 6. Rod enclosed in recurving
• 7. Enclosure or island
• 8. Dot
• 9. Short ridge
• 10. Long ridge
• 11. Incipient ridges
• 12. Ending ridge

# More Fingerprint Definitions

Pattern area—That part of a loop or whorl pattern in which appear the cores, deltas, and ridges, which we are concerned with in classifying. (The pattern areas of loops and whorls are enclosed by type lines—a plain arch pattern is often referred to as an absence of pattern due to the lack of deltas, type lines, or a defined core.)

Type lines—The two innermost ridges that start parallel, diverge, and surround or tend to surround the pattern area (Figure 2.6).

Core—The approximate center of the fingerprint pattern. (A loop pattern has specific rules governing choices between cores.)

The delta—The delta is that point on a ridge at or in front of and nearest the center of the divergence of the type lines (Figure 2.6).

What is the importance of fingerprints or how can fingerprints be used? Fingerprints can be used for both criminal and noncriminal purposes. In criminal matters, the obvious uses are to place a suspect at a scene of a crime, or to place or associate possession of a particular item with a suspect. This assists in the investigation by proving or disproving a set of facts or

Figure 2.6 Plain loop pattern; core, delta, and type lines illustrated: C, core; D, delta; T, type lines.

circumstances. Fingerprint evidence can also serve to corroborate information or statements. In noncriminal matters, commonly referred as civil matters, fingerprints are of use for identification purposes in disasters. Unfortunately, fingerprints cannot be used in all instances. Forensic odontology or DNA profiling may be utilized in those instances where fingerprints cannot be used. However, because of the ease of use and understanding, as well as the speed with which fingerprints can be used, fingerprints are the first choice of many experts.

Other issues that are important to include in fingerprint discussion:

There is strong evidence that fingerprint patterns tend to run in families.

A bifurcation is the forking or the dividing of one ridge into two or more ridges (Figure 2.6).

A divergence is the spreading apart of two ridges that have been running parallel or nearly parallel (Figure 2.6).

Finally, angles are never formed by a single ridge but by the abutting of one ridge against another (two ridges involved). Therefore, an angular formation can never be used as a type line.

Focal points or target areas are those areas within the pattern that contain ridge characteristics (Galton details) which are used for comparison and classification. (Galton details or ridge characteristics are contained in the second level of the comparison process. This level is discussed in the material on conducting fingerprint comparisons.)

## Study Questions

• 1. What is anthropometry?
• 2. What are the principles on which anthropometry is based?
• 3. What are the components of the Bertillon system?
• 4. What are the components of portrait parle as devised by Bertillon?
• 5. What are the values of the Bertillon system?
• 6. What are the shortcomings of the Bertillon system?
• 7. What was the West case, and what impact or effect did it have on criminal identification?
• 8. What is meant by the term portrait рагШ
• 9. Has the use of fingerprinting made portrait parle obsolete?
• 10. What do the terms dactylography, dermatoglyphics, and dactyloscopy mean?
• 11. What is a fingerprint?
• 12. What is the friction skin?
• 13. When is the friction skin formed?
• 14. What is a friction ridge? A furrow?
• 15. What is the basis for the science of fingerprints?
• 16. Define fingerprint identification.
• 17. Define the pattern area.
• 18. Identify the various ridge characteristics.
• 19. What are the types of fingerprint patterns (the main types and subtypes)?
• 20. Define fingerprint classification.

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