What is DNA fingerprinting?
DNA fingerprinting was the greatest achievement of the late 20th century which brought a revolution in forensic research. Fingerprint identification is primarily used for an accurate method of personal identification. The ability to identify people with simple fingerprints is a powerful tool in the fight against crime. It is the most common application of forensic evidence, often outperforming other identification methods. This progress in forensic DNA analysis helps charge offenders, acquit those wrongly accused, and identify victims of crime, disaster, and war.
History of fingerprint
Sherlock Holme found chemical reactions that activate hemoglobin in 1886. Hemoglobin is a red protein containing iron in red blood cells that carry oxygen. 100 years later, Alec Jeffreys discovered heritable repeating DNA sequences and variables at University of Leicester in UK. The first case of fingerprinting was regarding immigration in 1985. Although it was not technically a forensic case, it prevented a young boy from expulsion which seized the public’s sympathy. Nevertheless, the forensic implications of genetic fingerprinting were evident, and improvements in laboratory processes had led to the first application in forensic cases in 1987. The 1990s was the peak of DNA fingerprinting with twenty years of engineering, execution, and high throughput. Since then, technology has developed more and more.
How fingerprint works
There are three fundamental concepts of fingerprinting: uniqueness, permanence, and classifiable.
First of all, fingerprints are special. There are no two objects with the same ridge characteristics, accepting fingerprint evidence in court under the assumption that no two people have the same fingerprint. This principle has been validated not only by theoretical calculations but also by millions of people who have classified their fingerprints over the last few years. The FBI has approximately 50 million fingerprint records on its computer database, but they are identical to two other people's because it is impossible to find two fingerprints that are identical. The subtle characteristics of the ridge do not determine the pattern or shape but the personality of the fingerprint. The fingerprint's personality is determined by the number, relative position, and identity of the feature. Individuality is based on relative positions in print rather than numbers. A typical fingerprint contains 150 ridge characteristics. For many years, experts have discussed how many ridge features are needed to prove that two fingerprints are identical. Numbers ranging from 8 to 16 indicate that you meet the criteria for individuality.
Furthermore, a fingerprint is conserved throughout the course of a lifetime. The friction ridges that form on the palm side of the thumb and fingers are the fingerprints. These frictions are offered during childbirth to promote secure gripping and slide resistance. This friction skin is made up of a sequence of lines that represent ridges and grooves for hills and valleys, respectively. Each skin ridge contains pores that open to the duct that leads from the sweat glands, allowing the sweat and other substances that have been deposited on the skin to be expelled. Latent prints, which are not apparent to the human eye, are those that are created by perspiration. In the third or fourth month of pregnancy, friction ridges start to develop. When a wound penetrates the skin significantly, it destroys the dermal papillae, which changes or erases the fingerprint.
Lastly, the patterns on the fingerprints include loops, whorls, and arches. Loops are present in 60–65% of the population, whorls in 30–35%, and arches in roughly 5% of the population. The 10 fingerprint classifications may be used to categorize the prints using these three patterns.
Sir Henry in 1897 suggested changing from ridge patterns to alphabet and letter to arrange it as a fraction form. The ten fingers of both hands are categorizedinto five groups in the following way:
RIGHT THUMB AND RIGHT INDEX -16
RIGHT MIDDLE AND RIGHT RING – 8
RIGHT LITTLE AND LEFT THUMB-4
LEFT INDEX AND LEFT MIDDLE- 2
LEFT RING AND LEFT LITTLE -1
(Modern Forensic).
Once ten fingers’ values are collected, one is automatically added to the denominator and nominator. This fraction is also known as the primary classification. If any finger has loops and arch patterns, the value becomes zero. For example, if the RM and LI have a whorl pattern, but the other fingers have loops, then it will be: RT+RM+RL+LT+LR+1 / RI+RR+LI+LM+LL+1 which is equal to 0+8+0+0+0+1 / 0+0+2+0+0+1 =9/3.
There is a major classification that is only looking at the whorl and loop pattern of the left and right thumb. Other than the whorl and loop pattern on the left and right thumb will be zero.
The secondary classification is expressing the value of the left and right index in capital letter and fraction form. The right index should be at the nominator and the left index should be at the denominator.
Arch - A
Radial Loop - R
Whorl - W
Tented Arch - T
Ulnar Loop - U
RI/LI - Arch (A) / Whorl (W)
(Modern Forensic).
Fingerprinting plays a significant role in forensics. At the crime scene, it is much easier to arrest the criminal with fingerprints. With powerful fingerprint technology nowadays, fingerprint can be a strong evidence.
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