1. Fingerprint Patterns and Ridge Counts
Unit Two
Forensic Science
Notes 2.2

2. Three Patterns (Classes) of Fingerprints
(Eight Types)
Arch Patterns x2
Loop Patterns x2
Plain arch
Radial
Tented arch
Ulnar
(called a left or right loop if the hand from which it came is unknown)
Whorl Patterns x4
Plain whorls
Central pocket loops
Double loops
*Accidentals

3. The Archs

4. The Plain Arch
Formed by ridges entering from one side of the print and exiting on the opposite side. These ridges rise at the center, forming a wavelike structure.

5. The Plain Arch - count Connect the delta to the center Ridge Count = 0
(the delta is the center)

6. The Tented Arch
Similar to the arch, but there is either a sharp spike, or the ridges meet at an angle that is less than 90 degrees.
The center often resembles a tent pole.

7. The Tented Arch - count Connect the delta to the center
Ridge Count = 0
(the delta is the center)

8. The Loops
A loop must have one or more ridges entering from one side of the print, curving, and returning to the same side.
If a loop opens toward the little finger, it is called an ULNAR LOOP.
If it opens toward the thumb, it is a RADIAL LOOP.

9. The Loop – Ridge count
Connect the delta to the center core and count the number of ridges cross the line

10. Whorl Patterns

11. The Double Loop (A Whorl)
The DOUBLE LOOP is made up of any two loops combined into one fingerprint

12. The Double Loop – ridge count
Count the ridges that cross a line drawn between the delta

13. The Plain Whorl
These have at least one ridge that makes a complete circuit. This ridge may be in the form of a spiral, an oval, or any circular form.
A line drawn between the delta will intersect a circle

14. The Plain Whorl - count
Count the ridges crossing a line drawn between the delta.

15. The Central Pocket Loop (whorl)
The central pocket loop pattern consists a whorl embedded in a loop formation.
A line drawn between the deltae will not intersect a circle

16. The Central Pocket Loop
Count the ridges that cross a line drawn between the deltae