fingerprints, handprints have their own unique ridges. The ridges of
the fingertips continue down to the palm and can also be used for
Shoeprints can be lifted or developed in order to compare worn edges
or differences in the bottom of the shoe. The way a person walks
causes the shoe to be worn in a certain pattern and there will be
breaks or small rock indentations. Feet also have unique prints like
fingers that can be used to identify with a suspect print. When
dealing with shoeprints of footprints, there is a larger surface so
the characteristics are spread out and harder to mistake so fewer
points of comparison are needed for a positive identification than for
the thirty-two teeth in humans is unique due to age and wear. Bites
can tell how quickly the offender subdued the victim. Bites can often
be matched to dental records.
dentists assist in crime solving by studying teeth and teeth
impressions. Dental records are often used to identify people. Because
teeth are one of the hardest substances in the human body, they are
frequently well preserved. Dental x-rays or records showing fillings,
position of teeth, etc. can help forensic dentists find a match of
teeth to the individual. Eighty percent of the time teeth impressions
are used to identify unknown victims.
The retina is located
inside and at the rear of the eye. A retinal scan works on the
principle of retina pattern uniqueness. A retina scanner is used to
illuminate a region of the retina. It records the reflected
vasculature contrast information and maps the capillary pattern of the
retina. This type of scanning is considered exceptionally accurate.
Retina scanning works for user identification and verification.
Retinal scans use a low-intensity infrared light that is projected
through to the back of the eye onto the retina. The blood vessels on
the retina absorb the light faster than the eye tissue surrounding
them. This creates a pattern which is reflected back to the scanner.
The blood vessel patterns of the retina and the pattern of flecks on
the iris both offer unique methods of identification. Orientation
problems donít often occur because of the tendency of the eye to
naturally align itself as it focuses on a target that is illuminated.
A video image can be taken of the eye from one foot away so that the
person doesnít have to be in direct contact with the scanner.
Iris scanning can also be used for identification. In the iris alone,
there are over 400 distinguishing characteristics that can be used for
identification. These characteristics mean that the iris has six times
more distinct features for identification than the fingerprint and the
iris also remains unchanged throughout life.
The current problem for retina and iris scanning is user acceptance.
This type of identification isnít accepted by many people because of
the fear of eye damage, high costs and intrusiveness.