Page 76 - Automated Fingerprint Identification Systems (AFIS)

FINGERPRINTS ARE UNIQUE 61

3.4 DNA

Mug shots and fingerprints are not the only biometrics that can be used for
identification. Due to recent improvements in laboratory analysis and reduc-
tion in costs, many agencies are relying on deoxyribonucleic acid (DNA) as a
form of identification. DNA is a chemical structure that forms chromosomes.
A gene is piece of a chromosome that dictates a particular trait. That chemical
structure can be identified through laboratory analysis. Like fingerprints, DNA
does not change over time. Unlike fingerprints, however, two people can
have the same DNA. Identical twins share the same DNA, but not the same
fingerprints!
Large fingerprint identification services such as state identification bureaus
process hundreds, perhaps thousands, of requests each day. They respond to
these requests in hours, sometimes minutes. However, accommodating even a
portion of that number of DNA requests would grind the identification process
to a halt, as DNA identification processes require a relatively lengthy time
period.
In addition, some consider DNA collection to be much more personally inva-
sive than taking a rolled set of finger images. A booking officer putting a
subject’s fingers onto a glass platen to capture finger (and perhaps palm)
images creates a mind-set entirely different from the officer inserting a swab
held by a gloved hand into the subject’s mouth. The latter procedure assumes
the aura of medical analysis, an aura that can be viewed as too invasive.

3.5 FINGERPRINTS

3.5.1 PHYSICAL CHARACTERISTICS

Fingerprints are unique. The ridges on fingers are created during embryo
development in response to pressures that form patterns that can be classified
by print examiners. These ridges are also referred to as friction ridges. They
provide a relatively rough surface area, making it possible to grasp and hold on
to objects with ease. Each ridge contains at least one pore, which is connected
to a sweat gland below the skin.
The sweat gland helps to remove waste from the ridge area as well as to main-
tain a relatively constant temperature through evaporation. The sweat pro-
duced is also the source of deposits for latent prints, i.e., those finger images
that remain on a surface after it has been touched. In addition to water, the
sweat contains trace elements of oil and some minerals. These latent impres-
sions remain on the contact surface after it is touched. The condition of the
surface, e.g., if it is shiny or porous, affects how much of the sweat remains on