Fingerprints in Forensic Science – An Overview

Think of a crime scene where no crime weapon is present, no CCTV footage is available, no eye witness is there and the victim also passed away. What will the crime investigators do in such a case to identify the offender? How the actual culprit of the case will be held accountable? Well, let us tell you this is done through the analysis and examination of the fingerprints found at the scene and those of the suspects of the case. Fingerprints play a crucial role in the crime investigation process because of their unique feature of being distinctive. These prints play an important role in forensic science thus helping law enforcement agencies to solve the case in an efficient and fast manner. Here in this blog, we have given the complete details on fingerprints in forensic science and their relevance.

What Are Fingerprints?

The impressions of the patterns made because of the papillary ridges on the edges of the fingers and thumbs of a person are known as fingerprints. These prints are a unique feature of each individual present in this world hence considered to be a means of personal identification. The uniqueness of each individual’s fingerprints is because of the ridge arrangement on each finger. These prints reveal the identity of an individual, his appearance, trauma or accident the person might have faced, etc. because of being unique in nature since they do not change as a person grows old. The act of using fingerprints for identification of someone’s identity is known as Dactyloscopy.

Features of Fingerprints:

Fingerprints play a major role as evidence in the field of forensic science and hence are accepted throughout the world. There are some important features of these prints that made them universally accepted for crime investigation by law enforcement agencies. These factors are given below:

• Uniqueness:One of the most important features of fingerprints is their uniqueness. The patterns present on the fingertips vary from one person to another hence, they are different and unique. No two people have the same print patterns hence there are no chances since they remain unchanged throughout life thus maintaining the individuality of an individual. 
• Permanence:These prints are permanent and remain constant throughout the lifetime of an individual. The ridges of these prints start appearing during the third and fourth month of pregnancy and last till the death of an individual. If someone meets an accident and these lines are damaged then the ridges of these prints follow the prior pathways only. 
• Universal:For the investigation of case, law enforcement agencies needs something that is universal i.e. every individual has that marking. Since everyone in this universe has the prints on their hands and they act as a source of identification hence they are universal in nature. And since it is widely known that criminals leave their marks behind it is because they leave their fingerprints on the surface and hence provide the opportunity of getting leads in the case.
• Inimitable:Most people while committing the crime think of imitating or copying other’s fingerprints to hide their identity and falsify their presence at the crime scene. But the furrows and ridges present on the palms of an individual can’t be copied by anyone and hence no one can take the identity of an individual to commit a crime like forgery. 
• Uniqueness in Twins:When you look at twins, they seem to be identical in nature, or in simple terms we can say that they seem to be photocopies of each other. Twins are identical and share the same genetics but even their fingerprints vary and are unique in nature. 

How Are Fingerprints Collected?

The foremost step of using fingerprints in the crime investigation is their collection. The prints are collected after an examination of the crime scene. This is done through visiting the site along with the police personnel or crime investigation department officials. The process of fingerprint collection has been given below:

• Patent Prints: These prints are collected from the scene using simple methods of evidence collection like photography. The investigators take pictures of these prints through high-resolution cameras and examine those using forensic scales. To further enhance the quality of the images, such experts use chemicals, low or alternate light sources, dyes, etc.
• Latent Prints: These prints are collected from a smooth surface by dusting them with charcoal powder, black granular, flakes of aluminum, etc. This dusting is done to reveal the fingerprints hence take pictures of the same prints and thus to lift them using adhesive tapes. But the powder used for lifting can also contaminate the prints and therefore as an alternate, light sources are used
• Alternate light sources: With the increasing use of fingerprints in crime investigations, alternate light sources are gaining popularity. Examiners use this method to examine hard surfaces like doors, etc. In this method, the most commonly used light source is a laser or LED that emits particular wavelength light and provides different spectra for taking photographs and other related purposes.
• Cyanoacrylate: To get better visibility of the fingerprints on the non-porous surfaces, they are exposed to cyanoacrylate vapors. This is super glue and is used on a surface before applying powders or dye stains on the surface.  
• Chemical developers: To reveal latent prints on the porous surfaces chemicals like ninhydrin and physical developer are used. These chemicals react with the fingerprint residues and make them purple in color thus making them visible enough for identification.

Why Fingerprinting Is Used in Forensic Science?

When we think of fingerprints, we are often in dilemma about how such prints that are not even clear can help in the crime investigation. But those little marks or imprints created because of your palms are of great help in crime mysteries and are widely used by law enforcement agencies. These prints are used in mystery solving through their scientific implementation in the field of forensic science. These prints do not seem to be solid evidence but can tell a lot about the people associated with the crime.

Since fingerprints are impressions formed because of small ridges of the fingertips and are formed depending on how the fingers are placed on a surface or an object. The prints might be complete or partial in nature. When investigators find prints from a crime scene they try to match them with the prints of the suspects of the case. To compare the prints the law enforcement agencies take complete impressions of the fingers and thumbs using ink, electronically, etc.

Since these prints are unique to each individual and reveal major findings about a person, they are used widely by people for crime solving. These prints are the most reliable source of revealing the identity of an individual and hence are trusted by law enforcement agencies.

Comparison of Fingerprints:

The comparison of fingerprints is crucial in investigations and is often considered to be a defining factor in the identification of a person present at a crime scene. Apart from this, these prints also help in identifying the weapon used in committing the crime. Unlike other branches of forensic science, this branch is based on the experiment and analysis and not on the facts. Fingerprints can be classified into four groups based on the findings of the impressions found:  

• Identified:  The marks that can be confidently associated with a particular individual after a complete examination of the prints found at a scene. The final decision of the relationship of prints with that of an individual is made on the basis of matching of quality and quantity of fingerprints. 
• Excluded: In cases where the findings made after the analysis of fingerprint features do not match with that of a suspect, such prints are known as excluded ones. In such cases, the examiners start looking to match these prints with another suspect in the case. 
• Inconclusive: Cases where the impressions or the prints collected from a crime scene do not furnish enough information about the case or the suspect or victim and are not reliable for comparison are known as inconclusive prints. 
• Insufficient: In such cases where the fingerprints found at a crime scene are of low or poor quality and are less in number, these prints can’t be used for reliable comparison. Since the details are not clear for the purpose of comparison hence are called unreliable or insufficient prints. 

Thus from the above blog, it must be clear to you how relevant these fingerprints are in today’s world and in the era of crime investigation. When law enforcement agencies lose hope of finding the actual offender of the case or the suspects, these play a crucial role in determining the identity of individuals. Since these prints act as a symbol of person identification they tell us the entire details of the person. Things that can be figured out using prints include the age, gender, ethnicity, etc of the person. And because no two people have the same set of impressions formed by the ridges of the palm hence helps in identifying the culprit.

References:

• https://www.forensicsciences implified.org/prints/
• https://www.nist.gov/forensic -biometrics#:~:text=Fingerprint%20 analysis%20generally%20involves %20comparing,assessing%20how% 20similar%20they%20are
• https://www.azolifesciences.com /article/Fingerprint-Analysis-in-n Forensic-Science.aspx
• https://www.forensicsciencesi mplified.org/prints/how.html
• https://www.fingerprintexpert .in/blog-details/fingerprint-analysis- and-examination