1. Fingerprints Ch 17 Pgs 341-360 “Fingerprints cannot lie, but liars can make fingerprints.” - Unknown

2. Terminology Fingerprints – an imprint made by ridge patterns on the tip of a finger Minutiae – features within fingerprint patterns Henry system – an 10-print scheme for classification of fingerprints prior to AFIS AFIS – automated fingerprint identification systems Dactylscopy – the study of fingerprints (Greek daktulos – meaning finger)

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

4. What Fingerprints Are Fingers, palms, feet, and lips have “friction ridge” skin –Areas characterized by ridges and furrows –The ridge skin forms basic patterns in which there are numerous variations

5. Fingerprint Patterns There are 3 basic fingerprint patterns: arch, loop, and whorl An Arch goes from one side to another. A Loop starts and ends at the same side, which is the side of the opening. A Whorl is roughly circular, with the ridge lines going all the way around.

6. A closer look at Arches...... Arches can be plain or tented.. Plain Arch Tented Arch

7. A closer look at Loops..... Loops can be radial or ulnar, depending on which way the loop is pointing..... Radius – ‘Thumb’ side Ulna – ‘Pinky’ side

8. A closer look at Whorls.... Whorls are the most complex, having several categories; plain, central pocket, double, and accidental Plain Whorl Central Pocket Whorl Double LoopAccidental

9. Fingerprint Minutiae Features inside fingerprint patterns based on how the ridges form. ridge ending bifurcation dot island hook (spur) lake bridge

10. Primary Classification In the Henry-FBI Classification each finger is given a point value Can only be used on a 10-print set, which is grouped into pairs Right Left 4 8 8 16 16 4 2 2 1 1

11. Henry Classification Assign the number of points for each finger that has a whorl and substitute it into the equation R. Index + R. Ring + L. Thumb + L. Middle + L. Little + 1 = (16) (8) (4) (2) (1) ________________________________________________________ R. Thumb + R. Middle + R. Little + L. Index + L. Ring + 1 = (16) (8) (4) (2) (1) This is your classification number –For example: Ms Murphy 16 + 8 + 4 + 2 + 0 + 1 = 31 16 + 8 + 0 + 2 + 1 + 1 = 28 What’s yours? 31 28

13. Computer-based Fingerprint Files AFIS – consists of two types of files: –Knowns – contains the prints of known individual –Forensic database – contains images of prints from unsolved cases

14. Types Evidentiary Fingerprints 3 types of fingerprints –Patent – clearly recognizable, usually made by dirt, oil, grease, or blood –Plastic – (impression), a print indentation made in a soft substance (wax, butter) –Latent – requires additional processing to be recognizable (development) Powders, Chemicals

15. Development of Latent Prints Two methods: –Physical –Chemical Physical – lifting with powders –Carbon Black (dark) –Aluminum ( light) Chemical – lifting using chemical fumes –Iodine, ninhydrin, cyanoacrylate,

16. Special Fingerprints Fingerprints left by blood need to be processed in a special way –Lifted with a reagent –Photographed Fingerprints left on human skin are usually not able to be processed