Fingerprints

3 Fundamental Principles of Fingerprints A fingerprint is an individual characteristic; no two people have been found with the exact same fingerprint pattern A fingerprint pattern will remain unchanged for the life of an individual, however, the print itself may change due to scars or skin diseases. Fingerprints have general characteristics and ridge patterns that allow them to be systematically identified.

Principle One: Fingerprints are unique to an individual Minutiae, the major points of a fingerprint, are the characteristics that determine the individuality of a fingerprint, not the general shape or pattern. It is the identity, number, and relative location of these minutiae that creates the individuality of a fingerprint There are as many as 150 minutiae on the average finger *In judicial proceedings an expert must show a point-by-point comparison in order to prove the identity of an individual.

Principle two: Fingerprints remain unchanged unless scarred or diseased The epidermis is the outer layer or skin while the dermis is the inner lay of skin The dermal papillae is a layer of cells between the epidermis and the dermis The papillae are responsible for forming the ridges on the surface of the skin Once these develop on a human fetus, the pattern will remain unchanged throughout life, except to grow with the person

What is a Fingerprint? The ridges on the surface are there to help us with gripping things Water, oil, salts from our glands mix with dirt and other debris in the environment and then stick to everything we touch – leaving behind our unique fingerprint * Dactyloscopy – is the study of fingerprint identification. Police investigators are experts in collecting “dactylograms” (fingerprints)

Where do fingerprints come from? Where do fingerprints come from 2?

Principle three: Fingerprints have general characteristics and ridge patterns All fingerprints are divided into three classes on the basis of their general pattern: 1. Loops 2. Arches 3. Whorls *Think L.A.W

Principle Three: Loops Radial Loop (Right Thumb) Loop opens toward the left or the radial bone. Most Common – approximately 65% of all prints Loops must have 1 delta and 1 or more ridges that enter and leave on the same side The types of loops are named for their position in relation to the radius and ulna bones The point on a ridge at or in front of and nearest the center of the divergence of the type lines. The delta area is located as a triangular area where the ridges radiate outward in three directions *NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop. Delta Ulnar Loop (Right Thumb) Loop opens toward right or the ulna bone.

Principle Three: Arches About 5% of all fingerprints The simplest type of fingerprints that are formed by ridges that enter on one side of the print and exit on the other. No deltas are present. Tented Arches Similar to the plain arch, but has a spike in the center. Spike or “tent” Plain Arch Ridges enter on one side and exit on the other side.

Principle Three: Whorls About 30% of all prints Whorls have at least 1 ridge that makes (or tends to make) a complete circuit. They also have at least 2 deltas. If the print has more than two deltas, it is most likely an accidental. Plain Whorl Central Pocket Whorl 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.

Principle Three: Whorls Double Loop Whorl Double loop whorls are made up of any two loops combined into one print. Delta Accidental Whorl Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories.

Can you Identify these?

Can you Identify these? Worl R. Hand Ulnar Loop R. Hand Radial Loop

Try it again:

Try it again: L. Hand Radial Loop Whorl Arch

Fingerprint Identification