Fingerprints

Before Fingerprints

Will West

Now Wait a Minute William West

The Tale of the Tape Will West William West Body Height 178.5 cm Reach 187 188 Trunk Height 91.2 91.3 Width of Head 19.7 19.8 Length of Head 15.8 15.9 Length of Right Ear 14.8 Width of Right Ear 6.6 6.5 Length of Left Foot 28.2 27.5 Length of Left Middle Finger 12.3 12.2 Length of Left Little Finger 9.7 9.6

The Two Wests

Why Do We Have Fingerprints? Dermal Papillae

Ridges

Fundamental Principles of Fingerprints A fingerprint will remain unchanged during an individual’s lifetime. A fingerprint is unique due to minutiae. Fingerprints have general characteristics ridge patterns that permit them to be systematically classified.

Fingerprint Principles According to criminal investigators, fingerprints follow 3 fundamental principles: 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 permanent scars and skin diseases. Fingerprints have general characteristic ridge patterns that allow them to be systematically identified.

Fingerprint Classes There are 3 specific classes for all fingerprints based upon their visual pattern: arches, loops, and whorls. Each group is divided into smaller groups as seen in the lists below. Arch Plain arch Tented arch Loop Radial Loop Ulnar loop Whorl Plain whorl Central pocket whorl Double loop whorl Accidentical

60% of people have loops, 35% have whorls, Interesting Info Fingerprint Factoid: 60% of people have loops, 35% have whorls, and 5% have arches Did you know? Dactyloscopy is the study of fingerprint identification. Police investigators are experts in collecting “dactylograms”, otherwise known as fingerprints.

Arches Arches are 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.

Loops Loops must have one delta and one or more ridges that enter and leave on the same side. These patterns are named for their positions related to the radius and ulna bones. Radial Loop (Right Thumb) Loop opens toward the left or the radial bone. Ulnar Loop (Right Thumb) Loop opens toward right or the ulna bone. Delta 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.

Whorls 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. Central Pocket Whorl Plain 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.

Whorls – Part 2 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.

Comparison 1 Arrested 08-31-89

Comparison 2 Arrested 05-26-99

Comparison 3 Side-by-side Comparison

Comparison 4 Comparison of minutae points

Comparison 5 Labeled Points for Comparison

Print Comparison- minutiae

Why Do We Leave Latent Prints? Latent fingerprints are those that are “hidden” and are not visible to the naked eye. These prints consist only of the natural secretions of human skin and require treatment to cause them to become visible. Most secretions come from three glands: Eccrine--largely water with both inorganic and organic contaminants (salts) Apocrine--secrete cytoplasm and nuclear materials Sebaceous --secrete fatty or greasy substances.

Developing Latent Prints Developing a print requires chemicals that react with secretions that cause the print to stand out against its background. It may be necessary to attempt more than one technique, done in a particular order so as not to destroy the print. Powders--adhere to both water and fatty deposits. Choose a color to contrast the background. Iodine--fumes react with oils and fats to produce a temporary yellow brown reaction.

Iodine Fingerprint

Developing Latent Prints (cont) Ninhydrin--reacts with amino acids to produce a purple reaction. Cyanoacrylate--”super glue” fumes react with water and other fingerprint constituents to form a hard, white deposit. In modern labs and criminal investigations, lasers and alternative light sources are used to view latent fingerprints. It was first used by the FBI in 1978. Since lasers can damage the retina of the eye, special precautions must be taken and a filter used.

Ninhydrin Fingerprint

Cyanoacrylate Fingerprints

Other Prints Ears--shape, length and width Face--pictures being used in Florida to find criminals Voice--electronic pulses measured on a spectrograph Feet--size of foot and toes; lines of the feet Shoes--can be compared and identified by type of shoe, brand, size and year of purchase

Other Prints Palm--lines can be identified and may be used against suspects.

Other Prints Foot Prints are taken at birth as a means of identification for infants.

Other Prints Lips--display one of five common patterns Short vertical lines Long vertical lines Rectangular lines that may crisscross Diamond Branching

Other Prints Teeth--bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.

Other Prints The blood vessel patterns may be unique to individuals. They are used for today various security purposes.

“FINGERED” Crazy Criminals A New Jersey resident phoned police after finding her back door slightly ajar with a muddy palm print on the glass. When the officer questioned the woman, it was determined that she had been gardening. When he compared her hand with the lifted print, he had a match!!

Identify each fingerprint pattern. ? A B Right Hand Left Hand Answer Key: A - Plain Whorl, B – Double Loop Whorl, C – Radial Loop, D – Tented Arch, E – Plain Arch C Right Hand E D Right Hand Left Hand

It’s time to make some prints! Avoid Partial Prints GOOD PRINT Get as much of the top part of your finger as possible!

Directions 1st – Roll the “pad” portion of your thumb over the ink pad from the left side of your thumb to the right. You do not have to push down really hard! 2nd – Roll the “pad” portion of your thumb from the left side of your thumb to the right in the correct box on your paper to make a thumbprint. 3rd – Continue this process to make a fingerprint of all ten fingers on the “My Prints” worksheet. 4th –Use your notes and a magnifying lens to help you figure out what type of pattern is found in each of your fingerprints. Label each one with the pattern’s name.