1. Chapter 4 Fingerprints Fingerprint – impression of the
pattern of ridges on the last
joint of a person’s finger:
Unique – no one has one like yours
Never changes over a person’s lifetime
Systematic classification used for fingerprints

2. Major components of Fingerprints from Sweat
Na+ sodium
K+ Potassium
Ca++ Calcium
Fe++ Iron
Cl- Chlorine
F- Florine
Br- Bromine
I- Iodine

3. Dactyloscopy – the study of the fingerprints Greek word daktulos meaning finger.
Important Fact: Identical twins who have the same DNA fingerprint will have different fingerprints.

4. Diagram of skin

5. Classification of fingerprints
3 patterns:
loops, whorls and arches

6. Loops
Has one or more ridges entering from one side, curving, and then going out from the same side it entered from. Most common of all fingerprints (65% )
All loops have:
a delta: a triangular area, nearest the type-line divergence
a core: area found near the center
2 groups:
radial loop -5%: loop opens toward the thumb, toward the radius bone (shorter of the two bones in the forearm
ulnar loop –60%: loop opens toward the little finger, that is, toward the ulna bone the minor bone of the forearm.

7. Loops from the right hand
Radial loop ulnar loop

8. Whorls Fingerprint pattern with at least two deltas and a core.
(30 %) Plain 20%, other 10 %
4 groups
Whorl – General whorl can be located any where on the finger (not in the center of the finger)
Central pocket whorl – Whorl is located in the center of the finger
Double loop whorl – looks like a double S on it’s side
Accidental whorl – will be a combination of two or more. Very rare, only 10% of all fingerprints.

9. Whorls
(These are very similar)
Plain Whorl Central Pocket Whorl

10. Whorls
Double Loop Whorl Accidental Whorl

11. Arch
Are the least common and the simplest of all fingerprint patterns. They have no delta or cores. All ridges enter one side and exit the other side. Lines rise in the middle. (5%)
2 groups:
Plain Arch - 4%: wave like lines
Tented arch – 1%: more pointed lines

12. Arches
Tented Arch Plain Arch

13. Henry classify system is used to id fingerprints

14. A fingerprint is an individual characteristic, no two fingers have yet been found to posses identical ridge characteristics
Ridge ending – point at which a friction ridge ends or begins.
Island – dot or short ridge with ridges on either side.
Bridge
Enclosure – a friction ridge bifurcates and then converges to form a continuation of a single ridge
Delta
Bifurcation or fork – friction ridge that diverges or fords
Dot – very small portion of a friction ridge
Spur
Double bifurcation
Trifurcation

15. 3 Types of prints:
Plastic print – three dimensional prints made as indentations in soft material such as fresh paint, putty or wax: also called an indented or molded print.

16. Visible print – left by a finger that has touched colored material such as blood, paint, ink, grease, chalk, mud, or sometimes even dust.

17. Latent print – essentially invisible and must be developed by chemical or physical means. These prints result from deposits of perspiration and body oils.

18. Methods for lifting fingerprints
Fingerprint powders – applied lightly with a brush
Iodine fuming – iodine crystals are heated
Ninhydrin – reagent used to detect fingerprints, reacts with the acids in the prints to turn purple.
Silver nitrate – chloride ion of the salt will react/turns print black or reddish/brown
Super Glue fuming – good for nonporous surfaces, turns prints to whit
Ultraviolet light
Alternate light sources (ALS)

19. AFIS – Automated Fingerprint ID System – uses automatic scanning devices that convert the image of fingerprint into digital minutial that contains data showing ridges.