Forensics - Chapter 6

Fingerprints are protected by the outer layer of the

Epidermis

The type of powder used to dust prints will vary depending upon the weather conditions when the print is lifted.

False

How reliable is fingerprinting as a means of identification ?

Very

Fingerprints are in the womb at about

Week 10 of gestation

patent fingerprint

a visible fingerprint that happens when fingers with blood, ink, or some other substance on them touch a surface and transfer the pattern of their fingerprint to that surface

Silver nitrate

Reaction caused silver chlorine when the salt from sweat left on the print combines with silve

Iodine fuming

Reacts when it is combined with carbohydrates in a latent print

Ninhydrin

Reacts with sweat from the fingertips, the amino acids in the sweat cause this to react

Fingers consist of several main

Ridge patterns

Fingerprints left on a object are created by naturally occurring

Ridged in the skin of fingertips and secretions from sweat glands

Fingers have a core which is an area

Where ridges seperate or unite after running in a parallel direction

latent fingerprint

a hidden fingerprint made visible through the use of powders or other techniques ( not visible )

The presence of two deltas in a fingerprint indicate

a print is a loop pattern

Plastic fingerprint

a three-dimensional fingerprint made in soft material such as clay, soap (physically imprinted)

Outline the steps in taking a ridge count from a fingerprint.

1. Draw an imaginary line from the center of the core to the edge of the delta 2. Count all the ridges that touch or cross the imaginary line 3. The core and delta should not be included in the counting 4. Incipient ridges are never to be counted regardless of where they appearance.

Pudd'nhead Wilson

1894 - signature, physiological autograph

Fingerprints can be scanned at a resolution of

500 to 1000 dots per inch

The development of fingerprints happens in the

Basal layer of skin

The triangular region located near a loop pattern or whorl is called a

Delta

Can fingerprints be altered or disguised ?

Not permanently

IAFIS (Integrated Automated Fingerprint Identification System)

FBI-developed national database of more than 76 million criminal fingerprints and criminal histories

Fingerprints are formed deep within the dermis layer of the skin.

False

Fingerprints are generally considered to be a form of class evidence.

False

Fingerprints of the left hand are mirror images of the fingerprints on the right hand.

False

It is necessary to obtain a full print from a suspect in order to compare his fingerprint with a fingerprint found at the crime scene.

False

Plastic prints must be dusted or treated in order to identify the ridge patterns.

False

Similar print or ridge patterns can also be found on the toes.

False

How are latent fingerprints collected ?

Fingerprint Powders

Is it possible to alter fingerprints?

Fingerprints can be briefly altered by scratching the surface of your skin. The skin layers, however, are continually shedding and producing new skin, so that altered fingerprints grow back over time.

Summarize how fingerprints are formed.

Fingerprints form at or below the basal layer of the epidermis (the outer layer of skin is the epidermis). In a fetus, the basal layer grows at a relatively rapid rate which causes the development of folds and leads to the formation of ridges on the epidermis surface. Conditions within the womb affect the specific ridge patterns which make up our fingerprints.

The use of fingerprints in identification is not perfect because

The current technology depends on humans to analyze the information, and humans make mistakes.

Friction Ridges

The elevated regions in a fingerprint.

The materials we touch leave

Trace evidence on our fingers

Fingerprints are a result of oil and secretions from skin mixing with dirt.

True

It is important to always photograph a fingerprint before you attempt to lift it.

True

lAFIS improves the speed and accuracy of fingerprint searches because it electronically accesses fingerprints from local, state, and national agencies.

True

Fingerprints are formed

at 10 weeks' gestation (pregnancy)

Nanoparticles

have been added to fingerprint powders making poor patterns appear even sharper

Fingerprints that are actual indentations left in some soft material such as clay or putty are referred to as

plastic fingerprints

Cyanoacrylate

reacts with amino acids

minutiae

small or trivial details, trifling matters