Scenario: Unaltered Identity



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Chapter 6

Fingerprints

Scenario: Unaltered Identity
Introduction


  • Mark Twain would probably be impressed by how far the use of fingerprints to identify criminals has come today.

  • In 1894, Twain was writing about solving crimes based on unique identifying marks, fingerprints.

Historical Development



  • Several ancient cultures used fingerprints on official documents.

  • In western culture, the earliest record of the study of the patterns on human hands comes from 1684.

  • In 1823, Jan Evangelist Purkyn described nine distinct fingerprint patterns including loops, spirals, circles, and double whorls.

  • In 1879, Bertillon created a way of identifying repeat offenders through physical measurements.

  • Sir Francis Galton verified that fingerprints do not change with age. Galton and Sir E.R. Henry developed the classification system for fingerprints that is still in use today in the United States and Europe.

  • In 1891, Iván (Juan) Vucetich improved fingerprint collection and began printing all ten fingerprints.

  • In 1896, Sir Edmund Richard Henry created a system that divided fingerprint records into groups based on whether they have an "arch," "whorl," or "loop" pattern. Each fingerprint card in the system was called a ten card. These cards were imprinted with all ten fingerprints of a person and marked with individual characteristics.

What are Fingerprints?

  • All fingers, toes, feet, and palms are covered with small ridges that are raised portions of the skin, arranged in connected units called dermal, or friction, ridges. (Lips also have these ridges. The study of lip prints is called cheiloscopy.)

  • When these ridges press against things, they leave a mark, an impression called a fingerprint.

Formation of Fingerprints

  • Fingerprint patterns are formed during the 10th week of pregnancy.

  • Creation of the fingerprints happens in the basal layer of the epidermis of the skin.

  • These cells in the basal layer grow quickly and collapse and fold on top of each other.

Characteristics of Fingerprints

  • Fingerprint characteristics are named for their general visual appearance. These patterns and are called loops, whorls, and arches.

  • Two things a forensic examiner looks for on a fingerprint are the presence of a core and deltas.

  • A ridge count is another characteristic used to distinguish one fingerprint from another.

  • Basic fingerprint patterns of whorls, arches and loops can be further divided.

  • While looking at the basic fingerprint patterns can quickly help eliminate a suspect, in order to positively match a print found at a crime scene to an individual, more information is needed.

  • Every individual, including identical twins, has a unique fingerprint due to unique ridge patterns called minutiae (because the details are so small).

Types of Fingerprints

  • There are three types of prints found by investigators at a crime scene. They are patent, plastic, and latent prints.

  • Patent fingerprints, or visible prints, are left on a smooth surface when blood, ink or some other liquid comes in contact with the hands and is then transferred to that surface.

  • Plastic fingerprints are actual indentations left in some soft material such as clay, putty, or wax.

  • Latent fingerprints, or hidden prints, are caused by the transfer of oils and other body secretions onto a surface.

Fingerprint Forensic FAQs

Can fingerprints be altered or disguised?



  • John Dillinger, Public Enemy Number One in the 1930's, tried to alter his fingerprints, but essentially he made his fingerprints even more unique.

How reliable is fingerprinting as a means of identification?

How are fingerprints analyzed?

  • In 1999, the FBI developed IAFIS, the Integrated Automated Fingerprint Identification System, which provides digital, automated fingerprint searches, latent searches, electronic storage of fingerprint photo files, and electronic exchange of fingerprints and test results.

How are latent fingerprints collected?

  • Dusting surfaces with a fine carbon powder can make a fingerprint more visible. Tape can be used to ‘lift’ and preserve the fingerprint.

  • Metal or magnetic powders can also be used to lift fingerprints.

  • To recover a print from a surface that is not smooth and hard requires the use of different chemicals.

The Future of Fingerprinting

  • New scanning technology and digital systems of identifying patterns have helped to increase the processing time and clarity of fingerprints.

  • Technologies currently being developed use other physical features to identify people, including eyes, facial patterns, and the pattern of veins on the back of the hand or creases on the palm.


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