FINGERPRINTS

Fingerprints remain as the only means of positive identification. Although advances in DNA have been made in recent years, the results are still required to be expressed in statistical terms. Students will explore the nature of fingerprints in this portion of the course. They will look at the biology of friction skin and the chemical materials that make up a fingerprint deposit.

The students will learn to identify the structures, or minutia, that make up each of the different pattern types. Arches, loops, and whorls are described as first level details. Galton details such as ridge endings, bifurcations, dots, and enclosures are second level details. They were identified and named by Sir Francis Galton in the 1800's. Third level details consist of individual pores and the shapes of the edges of each ridge. Specialized training is required to be able to become an expert in this field.

                                                                                                 

 Students will be provided with actual fingerprints to identify pattern type and characteristic structures within them. They will also perform a comparison of inked to inked fingerprints to make an identification. Material from this unit will lead into the latent fingerprint unit which requires the application of this information.

 

Anthropometry  an identification system based on measurements of the human body developed by Alphonse Bertillon

Arch  fingerprint pattern formation that enters from one side, rises in the center, and exits the opposite side of the finger

Automated Fingerprint Identification System (AFIS)  a computerized system for the capture, storage, search, and examination of digitized fingerprint records

Classification  the division and grouping of fingerprints based on identifiable ridge structures and pattern types. The Henry system was most prominent formula used

Dermis  the underlying layer of tissue upon which the epidermis forms. It is the region which contains the papillae that serve as the base for friction ridges

Epidermis  The outer layer of skin which is comprised of living and dead cells that migrate to the surface and are eventually shed. It has five distinct layers.

Loop  fingerprint pattern which enters from one side, recurves, and exits from the same side of the finger from which it entered. It must contain a delta formation and a ridge count across a recurving ridge. Ulnar and radial loops are named for the bone of the lower arm on the side they originate.

Permanence  a characteristic of fingerprints describing their persistent presence and resistance to change from the time of formation prior to birth until after death.

Stratum Basale  is a single layer of cells that connect the outer layers to the dermis. It is the only place where new cells are produced.

Stratum Corneum  the outer 25 to 30 layers of dead cells that are constantly being sloughed off. All of these cells are dead.

Stratum Granulosum is made up of 3 to 4 layers of keratinized cells. Cells in this layer are dying and hardening.

Stratum Lucidum is only present in thick friction skin and the lips. Cell structures are not readily observed in this layer and prevent the transmission of UV radiation.

Stratum Spinosum mostly keratinocytes which are all alive.

Uniqueness  the characteristic of individualization that allows fingerprints to be used for positive identification

Volar Pads  raised formations that form as the basis for hands prior to the formation of fingers or ridge detail. Contours and pressure seem to

influence the pattern type formed on each digit.

Whorl  fingerprint pattern type comprised of a circular structure that must also contain at least two deltas. There are four basic types: plain, central pocket loop, double, and accidental.


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