Fingerprints

- The impression of the raised portions, or ridges, of the skin - imprint consists of natural secretions from sweat glands (water, oils, salt) and dirt
 * What are fingerprints?**

- formed during the 10th week of pregnancy - happens in the basal layer – layer in epidermis where new skin cells are produced - basal layer grows faster than the epidermis (outside) and dermis (inside) - when the basal layer folds and collapses, fingerprints are formed Other types of “prints” - palms, soles of feet, lips
 * How are fingerprints formed?**


 * Characteristics of Fingerprints**

__Loops__ – 65% of population - enter from either the right or left and exit from the same they entered

__Whorls__ – 30% of population - bull’s-eye with two deltas

- //plain whorl// – 24% - one or more ridges that make a complete spiral; two deltas; if line drawn between two deltas, at least one ridge in inner pattern cut by the line

- //central pocket loop whorl// – 2% - one or more ridges that make a complete circle; two deltas; if line drawn between two deltas, no inner patterns are cut by the line

- //double loop whorl// – 4% - two separate loop formations and two deltas

- //accidental whorl// – 0.01% - has two or more deltas and is combination of two of the other patterns

__Arches__ – 5% of population - enter from one side and leave from the other with a rise in the middle

- //plain arch// – 4% - enters one side, rises in center and exits other side without making an angle

- //tented arch// – forms and angle or may possess a characteristic of the loop patter (like a delta)

Pattern Pictures: http://ridgesandfurrows.homestead.com/fingerprint_patterns.html

- imaginary line drawn from center of the core to the edge of the delta and the lines in between are counted
 * Ridge Count**
 * Core** – center of a loop or whorl
 * Delta** – triangular region located near a loop

__minutiae__ – unique ridge patterns with small details - used to positively match a fingerprint - look at differences between ridges, number of minutiae, and location on a fingerprint - about 150 individual ridge characteristics on an individual fingerprint
 * Fingerprint Identification**




 * Types of Fingerprints** **and Methods of Collection**

__Patent fingerprints__ – visible prints left on a smooth surface

__Plastic fingerprints__ – indentations left in a soft material

__Latent fingerprints__ – hidden prints left by the transfer of oils or other body secretions; can be made visible with dusting or using a chemical reaction