Fingerprints

1. Fingerprints

2. Fingerprints– marks left behind when someone touches an object with their fingers. • Impression left in something soft – soap, wet paint, clay • Print left by a hand covered in dirt, blood or paint • Invisible deposit left by oil and perspiration secreted from the skin’s pores – “latent”

3. Everyone is unique • Fingers, thumbs, toes, lips, palms, soles of feet are all unique • Even identical twins are unique • Formed around 12th week of pregnancy • Will never change – even if injured – will grow back as skin heals • As body grows, fingerprints grow

4. Three main patterns • Arches • Loops • Whorls

5. Can be divided into smaller groups: Arch: plain arch, tented arch Loop: radial loop, ulnar loop Whorl: plain whorl, central pocket whorl, double loop whorl, accidental whorl

6. Trends in Certain Populations • In Western European populations, the loop accounts for about 60% of all prints. • Whorls and composites make up about 35% • Arches found in about 5% of all prints • Loops most common among black Africans • Central Europeans – arches most common

7. Staple or tape your fingerprint cards to the top of a piece of notebook paper, leaving space below each card to write some information. • Using your fingerprint cards, identify the patterns on all ten fingers. Record on your paper below the card piece of paper. • Make a chart below the cards: • Record the number of each pattern you have on your ten fingerprints.

8. Class Data • On board, record your data from the table • Create a bar graph showing the class data for each type of fingerprint.

9. Deltas

10. 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. 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.

11. 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.

12. 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 Whorls – Part 2

13. 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. Delta Ulnar Loop (Right Thumb) Loop opens toward right or the ulna bone. Radial Loop (Right Thumb) 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.

14. Fingerprint Minutiae

15. In some jurisdictions there must be a certain number of characteristic points in common if two fingerprints are to be accepted as a match. In most jurisdictions, there is no minimum number of points of identity required.

16. When are fingerprints taken? • When a crime has been committed, all people known to have been at the scene need to be taken • Suspects are fingerprinted so they can be investigated further or eliminated from further inquiries – “elimination fingerprints”