1. Everything you wanted to know and more!
FINGERPRINTING
Everything you wanted to know and more!

2. A BIT OF HISTORY
3,000 years ago the Chinese used fingerprints to sign legal documents.
1883 Alphonse Bertillon developed a system of body measurements to identify individuals instead of fingerprints…this was used for 20 years.

3. The Will West Case
A man named Will West was
arrested. His measurements
were taken for identification,
then he was told that he was
already an inmate at the prison
under the name William West.

4. The Mug Shots: One is Will West, the other is William West
They claimed they weren’t related.

5. The Fingerprints (West Case):
Their fingerprints were very different.

6. So What’s the Deal with the West Case?
It was later determined that Will West
and William West were identical twins.

7. Three Fundamental Principles Fingerprints….
Are an individual characteristic- no two have been found that are exactly identical.
Remain unchanged during a person’s lifetime.
Have general characteristics that allow for classification.

8. Individual Characteristics
Ridge Patterns (aka minutae)- their number, identity, and relative location
are unique to each person
Experts make at least 12 points of comparison between prints to prove a match.

9. Digital Print Comparison

10. Prints Remain Unchanged
Fingerprints are formed by the papillae, a layer of tissue found between the epidermis (outer layer of skin) and the dermis (inner layer of skin).
Papillae
(wavy black line)

11. Fingerprint Classification
There are three basic categories
LOOP
WHORL
ARCH

12. LOOPS
60-65% have loops
Lines enter one side, loop around, and exit the same side.
One delta (triangular pattern)

13. WHORLS
30-35% Have whorls
Rounded or circular pattern
Two Deltas

14. ARCHES 5% Have arches Lines enter from one side and exit the other.
NO Deltas

15. A FEW FINGERPRINT RIDGE CHARACTERISTICS
ISLAND
RIDGE ENDING
ENCLOSURE
BIFURCATION

17. Prints At The Crime Scene
Visible Prints - made by a finger stained with blood, food, paint, ink, etc.
Plastic Prints - Prints pressed into a soft surface like clay, soap, or wax
Latent Prints - Invisible prints left by body oils and greases

18. LOCATING LATENT PRINTS
For hard nonporous surfaces, such as glass, plastic, mirrors, tile, and painted wood- use dusting powder or Superglue fuming
For soft, porous surfaces such as paper, cardboard and cloth- use Iodine fuming or other chemicals

19. Methods for Locating Latent Prints
Dusting for Prints
Chemical Processing

20. PRESERVING THE PRINT FOR EVIDENCE
Always photograph the visualized latent print before further analysis for future comparison and evidence.

21. LIFTING A DUSTED PRINT
After dusting and photographing the print, a piece of tape (like Scotch tape) is placed over it. The pattern of the dusted print is transferred to the tape which is then mounted on a piece of contrasting colored cardboard.

22. Printing methods we will use in class
Inking and classifying prints
Dusting with powder & lifting
Superglue Fuming
Iodine Fuming