1. Fingerprinting
Forensics 352

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

3. Anatomy of Fingerprints
Will two people ever have the same fingerprints?
No two people have the same ridge characteristics…even identical twins!!!
Where can ridges be found?
Ridges can be found on you palms, feet, and lips.

4. Anatomy of Fingerprints
Skin is composed of an epidermal outer layer and a dermal inner layer.
In between the epidermis and the dermis, finger-like papillae press into the epidermis causing friction ridges.

5. Anatomy of Fingerprints
When the ridges press against objects, they leave an impression.
The impression consists of natural secretions of the sweat glands.
The secretions are a combination of water, oils, salt, and dirt.

6. Fingerprint Basics The core is the center of a fingerprint.
A delta is triangular area found on a fingerprint.

7. Categories of Fingerprints
A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta.
Subcategories
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?
1. Loop (65%)

8. Categories of Fingerprints
Whorls have at least two deltas and a core.
Subcategories
Plain: at least one ridge makes a complete circuit
Central pocket: no recurving ridge is touched in the pattern
Double loop: made of two loops
Accidental: a pattern not covered by other categories
2. Whorl (30%)

9. Categories of Fingerprints
2. Whorl (cont.)
Distinguish between Plain and Central Pocket Loop
Draw in the pattern, which is a line between the two deltas.
If the pattern line loops and touches the line twice - Plain
If the pattern line loops and does not touch the line - Central Pocket Loop

10. Categories of Fingerprints
3. Arch (5%)
Arches have 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 deltas or cores.
Subcategories
Plain
Tented

11. Ridge Characteristics
Fingerprint analysis is done by careful study of ridge characteristics also called minutiae.

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