Fingerprints are the most commonly used physiological trait of a biometric authentication system. The biometric system operates by acquiring the data from the user and comparing it with the data stored already to verify the identity. The matching accuracy of the system relies on the stability of the biometric data associated with the individual over some time. Society’s concern is to secure information and ensure personal privacy, which is greatly achieved by the various biometric techniques.
Fingerprints are very distinctive and the details are permanent even if one has temporary cuts and bruises. This technique has been used in criminal investigations. It can be scanned either by ink impression or by a live fingerprint scanner.
One very well-known example of the standard biometric evaluation is observed in the movie ‘Theeram Adhigaram Onru’ where Tamil Nadu police used fingerprints in jail registers to find the gang that robbed the houses on the highways. This method involves the manual identification of fingerprint pattern.
Dactyloscopy is the science of using an individual’s fingerprints and physical representative to identify the person.
EgliAnthonioz, N., & Champod, C. (2014). Evidence evaluation in fingerprint comparison and automated fingerprint identification systems—Modeling between finger variability. Forensic Science International, 235, 86-101.
This fingerprint biometric system continues to be the leading technology in terms of market share. It contains detailed pixel information from the friction ridges and valleys of the image. It generally has two categories: Touch and swipe sensor.
There are three kinds of fingerprints in a crime scene:
- Latent – Invisible
- Patent – Visible
- Plastic – Semi-visible fingerprints.
Let us discuss the case study of Finger Print:
This is a case study published on September 2019 that dealt with a complicated murder case that was solved with the aid of fingerprints. A typical murder case was encountered by the Dubai police on 26th April 2016. It was observed that the dead body was found in an apartment that bore some strange marks on the nose and was tied abruptly on the floor using different types of adhesive tapes.
The dead body has been tied along with the big bottle of water and a piece of paper that has red powder over it. All the items were collected from the crime scene with many precautions and had been submitted for the test. The challenges faced by the forensic and fingerprint experts are:
- Removing the tape from the dead body. But at the same time the tape must not get destroyed or not get adhere to itself since it may destroy the evidence.
- Transferring the powder from the paper. The powder was present in traces, so it must be handled properly to transform into a container for further queries.
- To find the suspects within the stipulated time, because pressure was much on the experts to provide the result.
- To collect the evidence such as fingerprints and other impressions.
Fingerprints were the main focus of the cops since they could directly reveal the person involved
The main objective is to show the significance of friction ridge impressions as a vital tool in such crime investigations. Fingerprint experts collected and found all the fingerprints from various pieces of evidence.
The oblique lighting technique is the most commonly used one and it has been also used here to locate details by creating shadows on the surface of the evidence. It uses a light source positioned at low/separate angles. The development of latent fingerprints is achieved by Cyanoacrylate fuming.
It is a crucial method for the development of fingerprints composed of sweat and oily body secretions. To complete the analysis and to enhance the process, standard fingerprint powders or fluorescent dye can be used to make visible prints under UV light.
In this case, the Dubai Police Forensic lab has performed various examinations on the collected evidence. During fingerprint development, there are two types of techniques such as destructive and nondestructive and most of the chemical techniques and powder methods are considered to be destructive.
Here, cyanoacrylate (superglue) was used on the collected water bottle, then ninhydrin was used on the piece of paper to preserve the fingerprint. Ardrox dye was used to stain the latent fingerprint using UV light.
The Automated Fingerprint Identification System (AFIS) was used finally to compare the suspects’ prints with the database. The software and computer system for automatic fingerprint interpretation, classification, and coding are in good progress these days. AFIS plays a major role here to identify the culprit in this case.
The quick processing of the chemical department and the comparison section helped to reveal the suspect in less than 24 hours. AFIS has been successfully used in the last two decades and the preceding steps involve fingerprint matching as the prevalent structure of the Fingerprint Identification System.
This case totally reflected the accuracy, precision and reliability of those fingerprint experts who found 29 fingerprints from the crime scene in less than 24 hours and all the 29 prints were positively identified. Cyanoacrylate served as the best method in this case. Though it was a complicated one due to the appropriate selection of the techniques, it resulted into a successful analysis.
Click to learn about the biometric technology used in Vikram movie
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