Fingerprint PrinciplesAccording to criminal investigators, fingerprints follow3 fundamental principles:• A fingerprint is an individual characteristic; no twopeople have been found with the exact samefingerprint pattern.• A fingerprint pattern will remain unchanged for thelife of an individual; however, the print itself maychange due to permanent scars and skin diseases.• Fingerprints have general characteristic ridgepatterns that allow them to be systematicallyidentified.
Fingerprint ClassesThere are 3 specific classes for all fingerprints basedupon their visual pattern: arches, loops, and whorls.Each group is divided into smaller groupsas seen in the lists below.ArchPlain archTented archLoopRadial LoopUlnar loopWhorlPlain whorlCentral pocket whorlDouble loop whorlAccidentical
Interesting InfoDid you know?Dactyloscopy is the study of fingerprint identification.Police investigators are experts in collecting“dactylograms”, otherwise known as fingerprints.Fingerprint Factoid:60% of people have loops, 35% have whorls,and 5% have arches
ArchesArches are the simplest type of fingerprints that are formed byridges that enter on one side of the print and exit on the other.No deltas are present.Plain ArchRidges enter on one side andexit on the other side.Tented ArchesSimilar to the plain arch,but has a spike in the center.Spike or “tent”
LoopsLoops must have one delta and one or more ridges that enter andleave on the same side. These patterns are named for their positionsrelated to the radius and ulna bones.DeltaUlnar Loop (RightThumb)Loop opens towardright or the ulna bone.Radial Loop (RightThumb)Loop opens toward theleft or the radial bone.NOTE: On the left hand, a loop that opens to the left would be an ulnarloop, while one that opens to the right would be a radial loop.
WhorlsWhorls have at least one ridge that makes (or tends to make) acomplete circuit. They also have at least two deltas. If a print hasmore than two deltas, it is most likely an accidental.Draw a line between the two deltas in the plain and central pocketwhorls. If some of the curved ridges touch the line, it is a plainwhorl. If none of the center core touches the line, it is a centralpocket whorl.PlainWhorlCentralPocketWhorl
Whorls – Part 2Accidental WhorlAccidental whorls contain twoor more patterns (notincluding the plain arch), ordoes not clearly fall under anyof the other categories.Double Loop WhorlDouble loop whorls aremade up of any two loopscombined into one print.DeltaDelta
Identify each fingerprint pattern.Right HandLeft HandLeft HandRight HandRight Hand
It’s time to makesome prints!AvoidPartialPrintsGOOD PRINTGet as much of the top partof your finger as possible!
Directions1st– Roll the “pad” portion of your thumb over theink pad from the left side of your thumb to theright. You do not have to push down really hard!2nd– Roll the “pad” portion of your thumb from the left side ofyour thumb to the right in the correct box on your paper to make athumbprint.3rd– Continue this process to make a fingerprint of all ten fingerson the “My Prints” worksheet.4th–Use your notes and a magnifying lens to help you figure outwhat type of pattern is found in each of your fingerprints. Labeleach one with the pattern’s name.
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