Forensics Midterm Review Ch. 6 Fingerprints

A finger leaves an impression called a ________

Fingerprint

The imprint of a fingerprint consists of natural secretions of...

The sweat glands that are present in the friction ridges of the skin

The secretions from fingerprints are a mixture of....

Water, sweat, oils, and salts

In humans, fingerprints are developed at about...

10 weeks into gestation

Ridge patterns are found on the soles of our...

Feet, fingers, and palms

Types of fingerprints

-patent fingerprints

-Latent fingerprints

Patent fingerprints

-visible fingerprints left on smooth surfaces when blood, paint, grease, ink or some other material comes in contact with the hands and is transferred to that surface

Types of Ridge patterns

Loops, arches, whorls

The most common ridge pattern

Loops

Latent fingerprints

Invisible fingerprints caused by the transfer of oils and other body secretions onto a surface

They can be made visible by dusting with powders and limiting by using tape.

These are the most common types of fingerprints found at crime scenes

The least common pattern

Arches

Ridges that enter from one side of the fingerprint and leave from the other side, with a rise in the center

Arches*

1 delta

Loop

0 deltas

Arches#

2 deltas

Whorls

Be able to identify ridge patterns

Radial loop

- type of loop

-direction of the opening loop: Opens towards the thumb

Know and be able to identify minutiae on a fingerprint

-ridge ending

-island ridge

-bifurcation

-dot or island

-eye

-spur

-bridge

-delta

-core

-double bifurcation

-trifurcation

Ninhydrin

-Chemical that helps visualize latent fingerprints.

-used on paper products

-is the best method visualizing a fingerprint found on a matchbook

Cyanoacrylate vapor

-Chemical that helps visualize latent fingerprints

-This chemical is used on plastic, metal, glass

Fluorescent powder (not a chemical)

Helps uncover and visualize fingerprints on dark surfaces

AFIS system

Purpose: to scan and digitally encode fingerprints for high-speed processing

Greatly improved the ability to analyze and compare fingerprints