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The Toe Tag: Put your finger on it.

Human fingerprints have long been a forensic tool investigators use to identify criminals and bodies.



Fingerprinting has come a long way since the days of the detective with his trusty magnifying glass.

Made up of friction ridges in skin found on fingers, toes, palms and feet, they are unique to the individual. Even identical twins have different fingerprints.

Ours are developed during the first trimester of pregnancy by the baby’s movements within the womb and their purpose is to help us grasp and hold onto items. Fingerprints do not change as we age and can only be destroyed or altered by scarring due to chemicals and/or trauma, but those unique injuries and/or scars can actually further assist in making an identification of an individual.

Fingerprints are most commonly associated with criminal investigations due to their uniqueness and persistence, and fingerprinting has been dated as far back as 300 B.C. In China and 702 A.D. in Japan Historically, they were used for identification purposes, but the United States began utilizing fingerprinting in criminal investigation in 1902 and the FBI’s Identification Division was formed in 1924.

There are 3 types of prints that can be recovered from a scene: latent, patent and plastic. Latent prints are invisible to the naked eye and fingerprint powders are used to make visible and lift the print from its surface. Patent prints are two-dimensional — an example of this type would be a fingerprint in blood. Plastic prints are three-dimensional and can typically be found in wax, plastic or clay. Depending on the type of print and the surface, there are many ways to preserve and maintain a quality print for lifting by utilizing powders, dyes, and casting materials.

Additionally, there are three levels of analysis that can be used to assist in making an identification. Level one details include the three primary fingerprint patterns: loops, whorls, and arches. Level two details, also known as Galton characteristics, include more detailed features, and level three details include things like scarring and ridge width. Level one details alone are not enough for an identification — at least one second-level detail is required for identification, though only a quarter-inch of a print is required to conduct an analysis.

ACE-V is the name for a method in which fingerprints are examined. A stands for analysis, which means the examiner always starts with the unknown print first and then the known. C is for comparison where the unknown and known prints are compared. E stands for evaluation, which is determining if a match or print is inconclusive, eliminated or an identification. V is for verification which means another examiner will conduct the analysis again and come to their own conclusion.

Alas, not every fingerprint left at a crime scene is perfect and examiners deal with many incomplete and smudged prints that can make examination quite difficult and Known fingerprints or suspect fingerprints aren’t always on file or available.

The kicker? Toe- and footprints can also be used to identify the deceased or suspects? But you don’t see that one on CSI very often, do you?

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