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Fingerprint Characteristics

Fingerprint Characteristics.

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Fingerprint Characteristics

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  1. Fingerprint Characteristics

  2. As we have learned in our first lesson, a fingerprint is made of a series of ridges and valleys on the surface of the finger. The uniqueness of a fingerprint can be determined by the pattern of ridges and valleys as well as the minutiae points, which are points where the ridge structure changes. Did you know? The koala is one of the few mammals (other than primates) that has fingerprints. In fact, koala fingerprints are remarkably similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two. Ridgeology: The study of the uniqueness of friction ridge structures and their use for personal identification.1 1Introduction to Basic Ridgeology by David Ashbaugh, May 1999 Image from http://www.cs.usyd.edu.au/~irena/minutia.gif

  3. Characteristics of Fingerprints • Forensic examiners look for the presence of a core (the center of a whorl or loop) and deltas (triangular regions near a loop). • A ridge count is another characteristic that distinguishes one fingerprint from another. The count is made from the center of the core to the edge of the delta. Forensic Science: Fundamentals & Investigations, Chapter 6

  4. Characteristics of Fingerprints • There are 3 general fingerprint distinctions: ARCH WHORL LOOP About 5% About 30% About 65% of the population Forensic Science: Fundamentals & Investigations, Chapter 6

  5. Arch An arch has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores. Types • Plain • Tented Forensic Science: Fundamentals & Investigations, Chapter 6

  6. Arches Spike or “tent” Plain Arch Ridges enter on one side and exit on the other side. Tented Arches Similar to the plain arch, but has a spike in the center.

  7. Loop • A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta. • Types • Radial—opens toward the thumb • Ulnar—opens toward the “pinky” (little finger) • Which type of loop is this, if it is on the right hand? Left hand? Forensic Science: Fundamentals & Investigations, Chapter 6 ; Kendall/Hunt Publishing Co.

  8. Loops These patterns are named for their positions related to the radius and ulna bones. Delta Ulnar Loop (Right hand) Loop opens toward right or the ulna bone. Radial Loop (Right hand) Loop opens toward the left or the radial bone. 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.

  9. Whorl • A plain or central pocket whorl has at least one ridge that makes a complete circuit. A double loop is made of two loops. An accidental is a pattern not covered by other categories. Whorls have at least two deltas and a core. • Types • Plain, Central Pocket, Double Loop, Accidental Forensic Science: Fundamentals & Investigations, Chapter 6 ; Kendall/Hunt Publishing Co.

  10. Whorls 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.

  11. Whorls – Part 2 Double Loop Whorl Accidental Whorl Double loop whorls are made up of any two loops combined into one print. Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories. Delta Delta

  12. Identify each fingerprint pattern. ? A B Right Hand Left Hand C Right Hand E D Right Hand Left Hand

  13. Characteristics of Fingerprints • Basic patterns can be further divided: • Arch patterns can be plain (4%) or tented (1%). • Whorl patterns can be central pocket (2%), double loop (4%), or accidental (0.01%). • Even twins have unique fingerprints due to small differences (called minutiae) in the ridge patterns. Forensic Science: Fundamentals & Investigations, Chapter 6

  14. Ridgeology Did you know? The koala is one of the few mammals (other than primates) that has fingerprints. In fact, koala fingerprints are remarkably similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two. Ridgeology: The study of the uniqueness of friction ridge structures and their use for personal identification.1 1Introduction to Basic Ridgeology by David Ashbaugh, May 1999 Image from http://www.cs.usyd.edu.au/~irena/minutia.gif

  15. Ridge Characteristics Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

  16. Fingerprint Minutiae- characteristics of ridge patterns Forensic Science: Fundamentals & Investigations, Chapter 6

  17. Fingerprint Identification • When minutiae on two different prints match, these are called points of similarity or points of identification. At this point there is no international standard for the number of points of identification required for a match between two fingerprints. However, the United Kingdom requires a minimum sixteen points while Australia requires twelve. Forensic Science: Fundamentals & Investigations, Chapter 6

  18. Automated Fingerprint Identification System (AFIS) AFIS is a computerized system capable of reading, classifying, matching, and storing fingerprints for criminal justice agencies. Quality latent fingerprints are entered into the AFIS for a search for possible matches against the state maintained databases for fingerprint records to help establish the identity of unknown deceased persons or suspects in a criminal case. http://www.fdle.state.fl.us/CrimeLab/images/fingerrint%20comparison%20for%20afis.jpg AFIS Video Link: https://www.youtube.com/watch?v=ZKi1CKTRCQM

  19. Crossover Core Bifurcation (fork) Ridge ending Scar Island Delta Pore Ridge Characteristics EXAMPLE http://cnx.org/content/m12574/latest/properties.jpg

  20. Directions on getting your print 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.

  21. It’s time to makesome prints! Avoid Partial Prints GOOD PRINTGet as much of the top part of your finger as possible!

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