Fingerprint Midterm

What is a fingerprint?

A fingerprint is a pattern of intricate design consisting of friction skin ridges found on the palm side of the fingers and thumbs.

What are friction skin ridges?

Friction skin ridges are the raised portion of the skin, consisting of veins, capillaries, and sweat glands.

3 Premises of fingerprinting

1. No two people have the same fingerprints, and no one person has two fingerprints that are the same.

2. Fingerprints develop in the womb and stay until the late stages of decomposition.

3. All prints can be put into a classification.

Arch types

Plain arch and Tented arch

Whorl types

Plain whorl, Central pocket whorl, Double loop whorl, Accidental whorl

Loop types

Ulnar loop and Radial loop

3 types of unknown prints

1. Latent: unknown, non-visual

2. Patent: unknown, visual

3. Plastic: 3-D prints

What is a loop?

A pattern in which one or more ridges enter upon either side, recurve, touch or pass an imaginary line between delta and core, and pass out the same side.

3 requirements of a loop

1. Sufficient recurve

2. Delta

3. Must cross a looping ridge

Typelines

The two innermost ridges which start or go parallel, diverge, and surround or tend to surround the pattern area.

Delta

That point on a ridge at or nearest to the point of divergence between two typelines, and located at or directly in front of the point of divergence.

T of F: Delta can be placed on a bifurcation that does NOT open toward the core

False!

Core

The approximate center of the pattern.

In a loop, the core is placed…

On or within the innermost sufficient recurve.

Radial vs. Ulnar

Going toward thumb: Radial

Going toward pinkie: Ulnar

What does NCIC stand for?

National Crime Information Center

Tented Arch

A pattern which consists of ridges that enter from one side, form a sharp, steep, "tent-like" peak or upward thrust in the center, and exit the other side. Ridges either form an upthrust, a definite angle, or have 2 of the 3 characteristics of a loop.

Angular type tented arch

• Formed by two ridges meeting at an angle. One continuous ridge cannot form an angle.

• Angle must be 90 degrees or less.

• If formed on the base ridge, angle must be exactly 90 degrees.

Upthrusting type tented arch

• An upthrust must end in space.

• An upthrust must make a definite change of direction from the base ridge. The upthrust must angle 45 degrees or more from the base ridge.

Recurving or looping type tented arch

Must lack one of the three basic characteristics of a loop: delta, recurve, looping ridge count

Plain arch

A pattern in which the ridges enter upon one side, make a rise or wave in the center, and flow or tend to flow out upon the opposite side.

Whorls

A pattern consisting of at least two deltas and at least one ridge that makes a complete circuit, which may be circular, spiral, or oval.

Plain whorls vs. Central pocket whorls.

Both patterns feature two deltas and at least one recurving ridge that makes a complete circuit. The core difference is, in a plain whorl, when an imaginary line is drawn between the two deltas, that line will cross or touch a circular ridge. In a central pocket whorl, that line will NOT cross or touch a circular ridge.

Double loop whorl

A pattern which consists of two separate loop formations with two separate and distinct sets of shoulders and two deltas.

Are s-type loop whorls double loop whorls?

No!

Are interlocking loops double loops whorls?

No!

Accidental whorl

A pattern which consists of a combination of two different types of patterns with the exception of the plain arch, with two or more deltas.

How to block an ulnar loop?

Slash

\ for right hand, / for left hand

How to block a radial loop

r

What goes in the top corner when blocking loops?

Ridge count

How to block a whorl

w

What goes in the top corner when blocking whorls?

Type (P, C, D, X) then Tracing (I,M, O)

How to block a plain arch

a

How to block a tented arch

t

What goes into the top corner when blocking arches?

NOTHING!

When doing NCIC, do you add 50 to an ulnar or radial loop?

Radial

Give NCIC for this…

1. Plain arch

2. Central pocket outer whorl

3. Ulnar loop, ridge count 11

4. Ulnar loop, ridge count 2

5. Tented arch

6. Plain meeting whorl

7. Radial loop, ridge count 7

8. Ulnar loop, ridge count 8

9. Accidental outer whorl

10. Double loop inner whirl

AA CO 11 02 TT PM 57 08 XO DI

Block this…

1. Accidental outer whorl

2. Plain arch

3. Tented arch

4. Ulnar loop, ridge count 7

5. Plain meeting whorl

6. Ulnar loop, ridge count 4

7. Double loop inner whorl

8. Radial loop, ridge count 14

9. Central pocket meeting whorl

10. Ulnar loop, ridge count 11

w^XO, a, t, \^7, w^PM, /^4, w^DI, r^14, w^CM, /^11