Loop Ridge Counting

Ridge counting defined: The number of ridges intervening between the delta and the core (Figure 3.19).

Procedure for ridge counting: An imaginary line is placed between the core and the delta. Each ridge that crosses or touches the line is counted.

• 1. The delta and core are not counted.
• 2. Where the line touches a ridge at the point of bifurcation, two ridges are counted.
• 3. Where the line crosses an island, both sides are counted.
• 4. Fragments and dots are counted only if they appear to be as thick and heavy as other ridges in the pattern (Figure 3.30).
• 5. A white space must intervene between the delta and the first ridge count, or the first ridge must be disregarded.
• 6. When the core is located on a spike that touches the inside of the innermost recurving ridge, the recurve is included in the ridge count only when the delta is located below a line drawn at right angles.

Figure 3.29

Figure 3.30

a. Counted (Figure 3.31)

b. Not counted (Figure 3.32)

Radial and Ulnar Loops

1. The terms have been derived from the radial and ulnar bones of the forearm.

Figure 3.32

a. Loops flowing in the direction of the little finger are ulnar loops.

b. Loops flowing in the direction of the thumb are radial loops.

i. Fingerprint cards: (manual/live scan)

ii. Right hand: Position as on the hand

iii. Left hand: The reverse

c. For purposes of automated use, loops are termed either right slanted (those patterns where ridges flow to the right) or left slanted (those patterns where ridges flow to the left).

2. Determining the direction of flow:

a. Begin at the core and follow or trace the ridges away from the delta.

b. From the recurve to the open end of loop.

Other Issues Pertaining to Loops

• 1. Sufficient recurve: The part of a recurving ridge between the shoulders of a loop. It must be free of any appendage abutting upon the outside of the recurve at right angles.
• 2. If a ridge enters on one side of the impression, recurves, and passes an imaginary line drawn between the delta and core but does not terminate on the side from which it entered, but has a tendency to do so, the pattern is a loop (Figure 3.34).
• 3. The recurve may take unusual forms (Figure 3.35).
• 4. The recurving ridge does not begin at the edge of the print, but possesses all the requirements of the loop (Figure 3.36).
• 5. The recurving ridge enters from one side, recurves, and turns back on itself. This is a loop pattern (Figure 3.37).

Figure 3.33 Loop ridge counts.

Figure 3.34

Figure 3.35

Figure 3.36