Fingerprint Examination

Alexis Wafstet
July 12, 2008
CJ242 Forensics/Lizotte
Project 1/Forensic Discipline


Fingerprint Examination is probably the most trusted and efficient ways to identify an individual. No two people in the world, not even identical twins, have the same fingerprint pattern. Fingerprints have been used as a form of identification since ancient times. It is believed that Ancient Babylonians used fingerprints to sign contracts as long ago as 2000 BC. Additionally, fingerprinting was used as a means of identification in 9th century China as a means to authenticate debt records. Although modern uses of fingerprint identification were not established until the 19th century, there is significant evidence that show fingerprinting was used throughout history as a positive means of identification.

According to Locard’s theory, whenever a person enters a location they leave something behind and take something with them. Fingerprints are left by transferring skin oils or secretions from the eccrine glands that are present in friction ridge skin. A friction ridge is a raised part of the epidermis on the palm or fingers of the skin, sometimes called the dermal ridges. These ridges have characteristic patterns known as loops, arches and whorls. Every fingerprint has one of these pattern types or variations included in the ridge formation. Friction ridges on the hands and feet also have other distinctive characteristics that are known as points. The first of these points are called bifurcations, which are when a single ridge splits into two ridges. Ridge endings are another point, which is established simply when a ridge ends. Dots are spots in the ridge formation that are unique to each fingerprint. These characteristics in friction ridge formations are what a Latent Print Examiner uses to compare and identify each unique fingerprint.

Fingerprint identification is the science of comparing latent prints, or those impressions left behind, with those that are known. A known print is one that is recorded on a smooth surface, usually with ink transferred onto a card. Latent print identification is based on levels of details including ridge flow, ridge formations and ridge path deviation. This means that comparisons are based on patterns, endings, bifurcations, dots, pores, ridge formation, and other unique details. A Latent Print Examiner makes these positive identifications based on the procedure known as ACE-V, which is an acronym for Analysis, Comparison, Evaluation and Verification. This is done by analyzing the friction ridges and determining their proportions, relationship and value toward comparison. There must be significant attributes observed in order for the print to be used as evidence. Without enough information to compare, the examiner may not be able to determine a conclusive match. Once the first analysis is complete, a second qualified examiner must compare the evaluation. This is to further verify if they agree with the first analysis and confirm the findings of whether or not the friction ridge impression is a positive match. If a fingerprint is lifted and a positive identification is determined, there is no doubt that person was at that location.

Latent prints are recovered many different ways. The first and most recognized technique is dusting. An examiner uses soft brushes to apply a fine powder to a nonporous surface. The powder sticks to the secretions left by the friction ridges of the skin. From there, the print can be photographed for comparison or simply lifted off of the surface using adhesive tape and then placed on cards to be preserved as evidence for later comparison. Porous surfaces are more difficult to recover prints from, as sweat and other residues are absorbed into the material. One method of recovering prints in this case is by using magnetic powders. They contain iron filings and when used with their special wands, the powder can be spread over prints. This procedure does not always work. In this case, examiners use a chemical known as ninhydrine, which reacts to the chemicals in sweat. Once heated, prints will appear purple and glow when hit by various lights, therefore making the prints visible for comparison. When checking for possible fingerprints, an investigator can also use special lighting techniques to determine if a print is on a surface that is not visible to the naked eye. From there prints can be photographed and lifted for further analysis.

Fingerprint evidence has been used in criminal courts to convict criminals as far back as 1892 in Argentina. The FBI began keeping fingerprint records of criminals in the 1890’s. Today, computer databases, like AFIS keep the nation and the world connected with millions of unique fingerprint records to use for comparisons. They have been the evidence needed to determine criminals in famous cases including John Dillinger, James Earl Ray, not to mention various Nazi supporters. Fingerprints are also used as one means of identification for the deceased when other methods are not available. This can be accomplished by rolling ink onto the fingers of the postmortem and transferring them onto a card. In some cases, an examiner must put their own gloved hand inside of the skin of the deceased in order to recover a print.

This area of Forensic Science is extremely fascinating to me for several reasons. To begin with, I want to have a career as a Crime Scene Investigator and this discipline truly suits me. I am detail oriented, and I love to analyze and research things. Secondly, it is exciting to me that no two people have the same fingerprints. With that in mind, I would be able to find the bad guy, without much doubt involved. Juries also have more faith in this area of Forensic Science, as it is one of the oldest and most trusted forms of positive identification of an individual. This would establish satisfaction in my career and I would know that I am personally making positive contributions to the Criminal Justice System. With these things in mind, Fingerprint Examination is a positive choice for me therefore, studying this discipline fascinates and excites me.

Works Cited:

Cole, Simon A. “Suspect Identities: A History of Fingerprinting and Criminal Identification”. Harvard University Press. Cambridge, Massachusetts. 2001.

Platt, Richard. “Crime Scene: The Ultimate Guide to Forensic Science”. DK Publishing. New York, New York. 2003 Dorling Kindersley Limited.

“Fingerprint”. www.wikipedia.org/wiki/Fingerprint. Last Modified: June 29, 2008. Printed: June 30, 2008. Wikimedia Foundation, Inc.