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Fingerprints and Forensics

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Each person is unique, whether it be because of their personality, their skills, or their appearance. But one specific item that can differentiate one person from another is their fingerprint. This impact of this simple–yet super complex–impression has notably paved the way for the scientific field of forensics. Nowadays, your fingerprint can be used to identify you, for example, when you want to open your phone. How are fingerprints created, and how has it contributed to the field of forensics?

What are fingerprints?

HowStuffWorks explains the specifics of fingerprints. When we touch the keys of a laptop, the handle of a door to open it, or a cup to drink water, we leave fingerprints on these surfaces. These prints are made up of tiny ridges, whorls and valleys–different lines–creating the shape of our fingers’ surfaces. There are 3 types of patterns formed by ridges; loops, which curve from one side of the finger to the other, whorls, that form a spiral-like pattern, and arches, which slope similar to mountains. When we apply pressure through our fingers, these prints appear on certain surfaces, leaving a mark on them. This is caused by the sweat glands present under our skin.

Image is courtesy of Pixabay.

The Use of Fingerprints in Forensics

Fingerprints are a reliable method of identifying a person, particularly because no two identical fingerprints have ever been found–each person’s print is unique. This is also the reason why according to the Canadian Society of Forensic Science, fingerprints have become an essential part of forensics science, the field of applying the scientific method to the judicial system. As a result, forensic scientists must use their scientific knowledge, research and background to enforce laws and governmental regulations within judicial investigations and hearings.

The National Forensic Science Technology Center (NFSTC) identifies two methods by which fingerprints are collected. During investigations, fingerprints may be collected as evidence to prove a certain condition within a case. Within such procedures, there are 2 types of fingerprints to be found: patent prints, and latent prints. Latent (or invisible) prints are prints formed by the body’s natural oil and sweat when it is deposited onto a surface. Such prints can be collected in a variety of ways, such as with the use of fingerprint powder, an alternate light source, or cyanoacrylate (a fuming procedure). On the other hand, patent (or visible) prints are created when a certain substance (such as blood, ink or paint) onto a surface. These can be collected using photography.

Analyzing Fingerprints

The NFSTC further explains how fingerprint analysis is conducted. When examiners decide to analyze a fingerprint, they use a procedure called ACE-V, which stands for Analysis, Comparisons, Evaluation and Verification. First, as part of the analysis, a print is assessed to be deemed suitable, as well as uncover any features that can help the next step, which is comparison. This is performed by an analyst, who looks at different prints of interests together to observe characteristics that may help to uncover a clue or hint helpful in a case. The evaluation stage then tests the examiner to decide whether or not the uncovered print is important to the case, or if it is inconclusive. Finally, during the verification stage, an external examiner goes through the first 3 steps independently to either confirm or reject the original examiner’s decision.

Reliability of Fingerprints in Forensics

According to the Criminal Justice Network, there have been multiple cases where the reliability of fingerprint evidence in court sessions were questioned. As fingerprints are a crucial part of an investigation, such questions caused people in the forensics department–analysts, statisticians, examiners, and researchers–to dig deep into such statements. While there still may be some topics under the use of fingerprints under debate, there are various factors that one can look at to determine its validity. Much of the reliability behind fingerprint evidence depends on the skill and experience the examiner has, which affects the quality of their results. If fingerprint evidence is re-examined and found faulty, or if the examiner has a record of having errors, this can be a warning regarding the validity of the evidence. However, it’s important to keep in mind that errors are inevitable in humans, and the innovation of new methodologies are what will allow forensics professionals to carry out their roles in the most reliable manner.

Final Words

It’s quite fascinating to see the identity that is hidden within the effortless imprint of your finger. Whether you decide to use fingerprints to unlock your phone or find the answer to an unsolved crime, it is evident that there is an immense amount of information stored on it, and that with more research, we will soon find new ways to use this biological tool!

Article Author: Asima Hudani

Article Editors: Victoria Huang, Maria Giroux