Illinois Law Enforcement Training and Standards Board (ILETSB) Practice Exam

What characteristic defines a fingerprint loop?

1. No deltas

2. Two or more deltas

3. One delta

4. Multiple whorls

The correct answer is: One delta

A fingerprint loop is characterized by having one delta. In fingerprint analysis, a delta is a triangular region where ridges converge and change direction. In the case of loops, this singular delta is usually located at the side closest to the axis of the loop, which helps in identifying the loop's classification. Loops are one of the three main types of fingerprint patterns, along with whorls and arches. They are defined specifically by their distinctive ridge flow and the presence of one delta. The singular delta is crucial in classifying the fingerprint and distinguishing it from other patterns. Understanding how loops are defined helps clarify why other characteristics, such as multiple deltas or the presence of whorls, do not apply to the classification of loops. The presence of two or more deltas indicates a whorl pattern, and having no deltas would not conform to the loop classification. Multiple whorls, as mentioned in one option, are entirely different patterns and are marked by the presence of circular ridge flows and at least two deltas.