A. Three basic patterns—loops, whorls, and arches Loop Whorl Arch

1. Loop a. = one or more ridges entering from one side, curving, then going out from same side entered b. contains a delta and a core c. ~ 65% of all fingerprints have loops

d. Subcategories of loop i. Radial loop = opens toward the thumb, which is toward the radius ii. Ulnar loop = opens toward the little finger, which is toward the ulna (NOTE: need to know which hand print came from to determine radial or ulnar loop... ulnar loops are more common)

Ridges flow in theRidges flow in the direction direction of the thumbof the little finger Radial LoopUlnar Loop Left Hand Right Hand Fingerprint Techniques Manual, page 13 --New Mexico Department of Health --

2. Whorls a. = contains at least two deltas and a core b. ~ 20% of fingerprints are plain whorls, ~ 10% are composite or accidental whorls c. Subcategories of whorl i. plain whorl ii. central pocket loop whorl iii. double loop whorl iv. accidental whorl

Whorls have at least one ridge that makes (or tends to make) a complete circuit. They also have at least two deltas. If a print has more than two deltas, it is most likely an accidental. Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl. Plain Whorl Central Pocket Whorl This slide:

3. Arches a. = all ridges enter on one side and exit on the other b. contain NO delta or core c. least common d. Subcategories of arch i. plain arch ii. tented arch Fingerprint Techniques Manual, page 9 --New Mexico Department of Health --

Fingerprint Techniques Manual, page 8 --New Mexico Department of Health -- cchspmanual/fingerprint_manual.pdf

B. Ridge classification (Individualization) 1. Minutiae = fine structure of ridge characteristics include... ridge ending bifurcation dot

core delta island (enclosure) short ridge

The computer database uses minutiae to compare fingerprints and determine a match.

Circle using the Promethean pen

 ures.html ures.html  print_manual.pdf print_manual.pdf

 If a fingerprint has no deltas, it is an arch.  If a fingerprint has one delta, it is a loop.  If a fingerprint has two or more deltas, it is a whorl. It’s time to take some prints! Info on slide: Click image for FBI instructions on taking fingerprints Image from: