Handprints                          

Just like fingerprints, handprints have their own unique ridges. The ridges of the fingertips continue down to the palm and can also be used for identification.

                           Footprints                                 

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 fingerprints.

   Bite Marks 

Each of 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.

Forensic 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.

 Retina Patterns               

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 don’t 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 doesn’t 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 isn’t accepted by many people because of the fear of eye damage, high costs and intrusiveness.