Abstract

For over a century, fingerprints have been regarded as one of the most reliable methods of personal identification in forensic science. Law enforcement and judicial systems rely heavily on fingerprints and finger markings as crucial evidence. The unique patterns in fingerprints—loops, whorls, and arches—are universal and distinct for every individual, even identical twins. These patterns serve as an infallible identifier, making fingerprints a cornerstone of forensic investigations. Whenever a crime is committed, the perpetrator often leaves traces in the form of fingerprints, either at the crime scene or on objects touched during the act. These marks are critical in linking the suspect to the crime, providing evidence that can stand up in court. Identification through fingerprint analysis is essential for ensuring that the guilty are held accountable while protecting the innocent from wrongful punishment. The scientific accuracy of fingerprint analysis further strengthens its role in criminal justice. The individuality and permanence of fingerprints mean they remain unchanged over time, adding to their reliability as evidence. By matching fingerprints found at a crime scene to a suspect, forensic experts can help establish guilt beyond a reasonable doubt, a crucial requirement in legal proceedings. This process not only aids in solving crimes but also ensures that justice is served by identifying the true offender. Fingerprints thus play an indispensable role in maintaining fairness and accountability within the legal system.

Keywords

Introduction

Evolution and Modern Applications of Fingerprint Identification

The science of fingerprint identification has evolved significantly, tracing its origins back to ancient Babylonia, where fingerprints were used to seal business transactions. Today, fingerprints play a crucial role in biometric security and serve as scientific evidence in international courts. The unique patterns formed by the elevated papillary ridges on fingertips, connected to sweat glands through pores, make fingerprints an unparalleled tool for identification. Remarkably, these ridges, formed during early fetal development, remain unchanged throughout life unless permanently altered by deep injuries. They even outlast other identifiable body features after death, making them a reliable form of identification. The distinctiveness, permanence, and universality of fingerprints have established them as a powerful investigative tool. Their ability to leave marks on any surface touched with bare hands has driven advancements in detection techniques. Fingerprint pioneers developed classification systems based on common patterns, such as loops, whorls, and arches, enabling the systematic organization and comparison of large fingerprint databases. Law enforcement and forensic teams use fingerprints to identify individuals, solve crimes, and even identify victims in disasters, emphasizing their critical role in criminal investigations and disaster management. One area of focus in modern forensic science is detecting fingerprints on porous materials like paper. Traditional methods, such as physical adsorption and biochemical reactions, face challenges such as pre-treatment requirements, health risks, and potential sample damage. The optical method, particularly laser-induced fluorescence detection, has gained prominence. Using lasers as excitation sources, this technique detects trace fingerprint substances by analyzing the emitted fluorescence. Ultraviolet laser-induced fluorescence stands out for its sensitivity, high resolution, and non-destructive nature. Despite its advantages, obtaining high-quality fingerprint images on paper remains complex due to paper’s diverse types and microstructures. Recent research explores the interaction between ultraviolet light and porous paper, analyzing fluorescence characteristics and differences across paper types. These studies, combined with advanced data processing techniques, enhance fingerprint detection on paper, offering precise evidence for criminal investigations. As fingerprints continue to be recognized as "human ID cards," they remain one of the most reliable and significant biometric technologies in modern forensic science.

Fingerprints: The Skin's Unique Identifier

The skin, one of the body's largest and most complex organs, plays a pivotal role in fingerprint formation. Comprising various tissue types, it serves as a protective, flexible barrier with a vast network of blood vessels and sensory receptors. The skin, alongside its derivatives such as hair, nails, and glands, forms the integumentary system. Within this system, the hands and feet are distinct, featuring friction ridges that aid in grip and contain dense clusters of pores and nerves. Friction ridges, particularly those on fingertips, are characterized by intricate patterns of peaks and valleys, interspersed with sweat pores. These features make the skin on fingertips uniquely suited to leaving behind latent fingerprints—trace impressions created by the transfer of sweat, oils, and other residues onto touched surfaces. Latent fingerprints are invisible to the naked eye but can be made visible through specialized techniques. One common method involves applying powder to adhere to the residue in the prints, revealing their patterns. Another approach uses iodine, which reacts chemically to discolor the print. Advanced technologies, such as laser light, are also employed to detect latent fingerprints. Laser-induced fluorescence allows for the visualization of prints, making them suitable for photographic documentation and further analysis. These methods underscore the significance of friction ridge patterns as unique, persistent identifiers. By capturing every detail of these patterns, forensic experts can unlock vital clues in criminal investigations, making fingerprints a cornerstone of modern forensic science.

Historical Background of Fingerprints

Fingerprints were utilised by the ancient Babylonian, Chinese, Persian, and Roman civilisations. The earliest known friction ridge skin impressions are believed to be these prints. The deposition of the prints found in ancient civilisations was not exact and clear since they were either intentionally or unintentionally created.  Fingerprints were found in clay tabs, seals, and ceramics used in Babylon to record deeds from the second millennium BC. When King Hammurabi ruled Babylon from 1792 to 1750 BC, police officers took the fingerprints of those who were arrested. These have also been seen in ancient Babylonian and Roman bricks and tiles, Egyptian tomb walls, and Greek and Chinese ceramics.
Throughout the Chinese Dynasty, fingerprints, hand prints, and footprints were collected and used as forensic evidence. By 650 and prior to 851 CE, Arab merchant Abu Zayd Hasan observed the usage of fingerprints for verification. Renowned Persian physician Rashed-al-Din Hamadani (1247–1318 AD) observed, "Experience shows that no two individuals have fingerprints exactly alike," alluding to the Chinese custom of using fingerprints to identify individuals. By 702, Japan also let its illiterate citizens to use their fingerprints to sign divorce papers.
In 1684, Dr. Nehemiah Grew provided the first detailed description of friction ridge skin. In India, Sir William Harschel began using fingerprints for deeds, contracts, and prisoner registration in 1877. In Kolkata, a fingerprint bureau was later formed. Two Indian fingerprint specialists, Azizul Haque and Hem Chandra Bose, were principally responsible for creating the Henry Classification System, which was named for their supervisor.  After doing more research, Sir Francis Galton presented information on fingerprint analysis and identification, demonstrating that the likelihood of a false positive fingerprint was roughly 1 in 64 billion. The first nation to use fingerprints exclusively for individualisation was Argentina. These days, it is utilised all around the world to identify individuals in any disputes or enquiries within the court's premises. 2019: The Biggest Database in the World The largest fingerprint system in the world, which uses iris, face, and fingerprint biometric records, is the Unique Identification Authority of India. Another name for India's Unique Identification project is Aadhaar. The aim of the voluntary Aadhaar initiative is to give the majority of India's projected 1.25 billion citizens valid national identification credentials. The Authority had issued over 1.11 billion (more than 111 crore) Aadhaar numbers as of January 2017.

Historical Background Of Fingerprinting In Context Of Different Countries

Ancient World: Despite human foolishness and modern technology, fingerprint forensics has a future. For thousands of years, people have utilised fingerprints as a means of identification. However, an experiment conducted 125 years ago by an Argentine statistician resulted in the use of these distinctive identifiers to solve the first murder. Juan Vucetich was a statistician and fingerprint researcher. In ancient Babylon, between 1000 and 2000 B.C., fingerprints were used on clay tablets for business transactions. In China, thumbprints were first employed to "sign" texts on clay seals in the third century BCE. Fingerprints are said to have been employed on official papers during the T'ang Dynasty (610–907 AD), when imperial China was one of the most powerful and affluent countries in the world. On a rock wall in Nova Scotia, a Petroglyph from the first century AD shows a hand with pronounced ridges and finger whorls, most likely created by the Mi'kmaq people

India: India may have been among the first countries to use fingerprinting as a means of establishing criminal activity. Sir William Herschel, the Chief Magistrate of the Hooghly district in Jungipoor, India, utilised fingerprints to "sign" contracts with indigenous Indians for the first time in 1858. All inmates in Bengal were required to have their fingerprints taken by British official Sir Edward Richard Henry in 1896. Additionally, he created his own system with 1,024 main groupings. A resolution mandating fingerprinting as the official means of identifying criminals in British India was signed by the Governor General within a year. Growing up in Japan in the 1880s, Dr. Henry Faulds, a British surgeon who served as the superintendent of Tokyo's Tsukiji Hospital, talked about fingerprints as a way to identify oneself and how to get them using printer ink.

United Kingdom: Sir Francis Galton started studying fingerprints in 1888, mainly to create amethod for identifying inherited characteristics and genetic history. Galton was the first to present scientific proof that fingerprints are unique and do not change over the course of a person's lifetime. According to his calculations, there was a 1 in 64 billion chance of discovering two fingerprints that were identical. Galton produced the first book of its sort, "Fingerprints," in 1892. In it, he described the first fingerprint categorisation system and distinguished three categories of minutia, or fingerprint characteristics: loop, whorl, and arch. These traits, sometimes known as Galton's Details, are somewhat still in use today. The establishment of Scotland Yard's Central Fingerprint Bureau was made possible by the "Henry Fingerprint Classification System" in India in 1901.

USA:  To prevent forgeries, Gilbert Thompson, who worked for the U.S. Geological Survey in New Mexico, put his own fingerprints on a document in 1882. In America, this was the first documented use of fingerprints for identification. In his 1883 novel "Life on the Mississippi," Mark Twain describes a murderer who is recognised by his fingerprints. Under the direction of Dr. Henry P. DeForrest, the New York Civil Service Commission began testing fingerprints in 1902, marking the first time that fingerprints were used systematically in the US. The Federal Bureau of Prisons, the New York State Prison system, and the New York Police Department started utilising the new science in 1903

Importance Of Fingerprints

Although it took some time for the public and judiciary to accept the value of fingerprints as a scientific tool, this is now acknowledged globally. The following characteristics make fingerprints an important piece of evidence:

Unique: The papillary ridges of the fingers feature intricate patterns that vary from one another. The patterns discovered are distinct and distinctive within an individual, in addition to varying from person to person. Pattern duplication has never been seen or anticipated.

Permanent: A person's fingerprints are permanent and don't change throughout the course of their lifetime. The ridges on the fingers develop in the third or fourth month of pregnancy, which is before delivery. Even after a person passes away, their fingerprints are left behind until the epidermal layer—the initial layer of skin—is destroyed by fire, insects, decomposition, or other organisms. Even surgically removing the epidermal layer is not an option, nor is it feasible to burn, cut, or rub away the ridges. Each person's fingerprints serve as their unique identity card.
Universal: Since fingerprints are a universal form of identification, every person possesses one. Any criminal who commits a crime with his hands leaves markings on the site of the crime or on any object that comes into contact with his hands during the commission of the crime. As a result, fingerprints might be found in every crime. Many offenders wear gloves when committing crimes, making it impossible to identify their fingerprints. Unmistakable: Fingerprints cannot be copied. Fingerprint forgeries have been tried, although no successful attempts have been documented to yet. This can be recognised by the investigating officer and specialists; while scientific progress may make forgeries even more precise, total success is quite challenging.
Classifiable: Since each person's fingerprints are unique due to their ridge patterns, fingerprint classification is simple. Millions of people's records can be categorised and accessed as needed.

Statutory Recognition Of Fingerprints In India

In India this fingerprinting technology has played a vital role in identifying the real accused. Such procedure has admitted in India by various legislations.

Constitution of India

It cannot be said that the police are denied this authority as long as there is no legal or constitutional restriction preventing them from collecting an accused person's sample handwriting and signature. Unlike a statement made to a police officer that may subject the suspect to criminal liability, the mere acquisition of the accused's handwriting or specimen signatures does not automatically result in criminal liability unless it is compared to the disputed statement and an expert's opinion is obtained. The Supreme Court has ruled unequivocally that providing the police with sample handwriting and signatures does not constitute testimonial compulsion, which is forbidden by Article 20(3) of the Indian Constitution. Therefore, the police are not prohibited by the constitution from obtaining an accused person's handwriting or signature samples.

Identification Of Prisoners Act, 1920

The Identification of Prisoners Act, 1920, Section 3, gives station house officers and investigating officers the authority to get the fingerprints of anyone found guilty of a crime. Any individual may request security of his good behaviour under Section 118 CrPC and, if necessary, consent to a police officer taking his measurements (including his finger prints) and photos in the way specified.  According to Section 4 of the Identification of Prisoners Act 1920, investigating officers and station house officers have the authority to obtain the fingerprints of non-convicted individuals who have been detained in relation to an offence. Any arrested person may be ordered by a magistrate to provide their fingerprints for any inquiry specified in the Code of Criminal Procedure. The magistrate may also order the collection of a person's fingerprints during a criminal trial. The Identification of Prisoners Act's Sections 5 and 6 as well as Section 73 of the Indian Evidence Act give law enforcement and courts the authority to take an arrested person's fingerprints for identification or investigation. In accordance with Section 6 of the Identification of Prisoners Act, appropriate steps shall be taken to secure a prisoner's finger prints if they refuse to provide them. He will face negative consequences and be subject to punishment under Section 186 of the IPC if he continues to refuse.  This act's primary goal is to give legal authority for the collection of measurements pertaining to the fingerprints, finger imprints, and photos of the individual who is suspected or accused of committing any crime. Finger impressions of criminals and suspected criminals were not legally sanctioned prior to the passage of this Act. However, as stated in S.3, it has now confirmed the collection of finger impressions and dimensions.
It specifies that everyone convicted of a crime carrying a harsh one-year jail sentence or more must provide their measurements for a police officer to take. Finger impressions are sometimes included in the word measures. Additionally, the Act requires that measurements be destroyed upon a court's discharge or acquittal. Measurement of non-convicted individuals is covered in S. 4 of the Act, which states that anyone caught for a crime carrying a harsh one-year jail sentence or more must consent to having their measurements taken. S. 5 gives the magistrate the authority to order anyone to consent to his measurements so that the investigation can be conducted.

Code Of Criminal Procedure, 1973

According to S. 293, the report that the Director of the Forensic Bureau submits can be used and accepted as proof. In essence, the goal of this part is to prevent unnecessary exams and save time. However, the court has the right to call the individual who submitted the report if specific concerns are raised by it.
A report provided by the Director of the Fingerprint Board as an expert opinion may be presented as evidence, per Section 293 CrPC. Any such expert may also be summoned and examined by the court if it deems appropriate. Palm prints are admissible in court under Section 45 of the Indian Evidence Act. Taking a sample of handwriting does not constitute making a statement for the purposes of Section 162 CrPC. The only source of authority to get the accused's signature and handwriting during an investigation is Section 311-A CrPC; to do otherwise would be to deny the police a power that has always been there. After the Supreme Court's recommendation in State of Uttar Pradesh v. Ram Babu Misra, Section 311-A was added to the statute about 25 years ago.
Indian Evidence Act, 1872

Legislators recognised fingerprints as legitimate evidence because of their significance, which stems from their uniqueness, permanence, universality, inimitability, and classifiability. Fingerprints are recognised as a legitimate form of evidence under the Indian Evidence Act, 1872.  According to S. 45, the opinions of those who are knowledgeable in a particular field will be taken into consideration when the court is asked to make a decision on a legal matter that involves foreign law, science or art, handwriting, or finger impressions. The phrase "finger impression" was initially left out of the section. The term "finger impression" was inserted by the Amendment Act of 1899. According to S.73, the court has the authority to order anyone in the room to provide their fingerprints if the court needs them to compare them to the fingerprints under question. According to Sections 45 and 73 of the Indian Evidence Act, a finger print expert's testimony is acceptable in court. When the court must make a decision regarding a matter of foreign law, science, or art, or regarding the identification of handwriting or finger impressions, the opinions of individuals who are particularly knowledgeable about those subjects are pertinent facts. We refer to these individuals as experts. If the court needs to compare a person's finger prints with a contested finger print, it may order anyone in the room to provide them. If oral testimony relates to a view or the principles upon which it is based, it must be the testimony of the individuals who hold that position in accordance with Section 60 of the Indian Evidence Act.
Judicial Approach on Finger Print

Evidence Fingerprint-based identification is so widely used that courts are unable to refuse to take it under judicial cognisance. Like other proof, this type of evidence is admissible if it tends to establish a case, regardless of its independent strength. Generally speaking, everything that tends to establish a material reality is competent and relevant. The fact that no two people have the same thumb markings is a logical inference from experience. The Thomas Herbert Castleton's Case of England, resolved in 1909, serves as a prime example of the courts' acceptance of fingerprint evidence. The Lord Chief Justice ruled that fingerprint evidence was admissible even though it was the only means of identification. Fingerprints were used to condemn Parker in Parker v. The King. In the People v. Jennings case, which is regarded as one of the seminal instances on the admissibility of fingerprint evidence, the court determined that the fingerprints taken from the crime scene were a conclusive match, marking the first actual identification of fingerprints in the United States. "The witness must have made a special study or acquired a special experience therein," it was noted in the case of United States Shipping Board v. The Ship "St Albans." In other words, he needs to be knowledgeable and skilled in the field. In Chitaman Dissil v. M. Lakshman, it was decided that "just having the chance to see fingerprints does not make one an expert." For an expert, the problem must be studied and viewed from a scientific perspective. According to the ruling in Jaspal Singh v. State of Punjab, the science of determining thumb imprints is precise and error-proof. According to the ruling in Govinda Reddy v. State of Mysore, the science of finger print comparison has advanced to an exactitude level. According to the ruling in Bhaluka Behara and others v. State, if the finger prints are sufficiently clear, the court must confirm the expert's testimony by comparing them to the materials that were gathered at the time of the examination and using its own judgement to determine whether the finger prints are similar or dissimilar before reaching a decision. The primary question to be examined, however, is whether the experts' analysis is comprehensive, scientific, and thorough. When experts are present on both sides, the court cannot simply dismiss the case by stating that one of the reports was difficult to like.

Fingerprints and Right Against Self Incrimination

The self-incrimination policy is one of the main governing issues of fingerprints. It has been disputed whether taking an accused person's finger prints constitutes self-incrimination. One of the primary protections in criminal proceedings is the right against self-incrimination. The first is to make sure the accused's statements are reliable, and the second is to make sure the accused's statements are supplied willingly. There are numerous opportunities for the individual who is considered a suspect or accused to be coerced or threatened during the course of his investigation, and the likelihood that he will provide false testimony increases when this occurs. False testimony causes a miscarriage of justice by misleading judges and even the prosecutor.
This right is a crucial defence against torture. The prosecution bears the burden of proving the charges against the prisoner during the trial, and the "Right against Self-Incrimination" is a crucial precaution to make sure the prosecution fulfils this obligation.

In Re Sheik Muhammad Hussain,^[1]it was held by the Madras High Court that when police acquire fingerprints for the course of investigation and which is later used in the trial procedure did not amount to testimonial compulsion under Article 20(3) and this is admissible as evidence. Because the test subject is not compelled to provide verbal responses, the involuntary administration of the BEAP and polygraph tests cannot be equated with testimonies compelled by law, according to the ruling in Selvi and others v. State of Karnataka (3). Furthermore, it was clarified that verbal disclosures made during a narcoanalysis are exempt from the bar of Article 20(3) since it is unknown at the time of the test whether the disclosures are exculpatory or inculpatory.
The Kerala High Court examined the protections against self-incrimination and the acquisition of handwriting that is obtained from an individual's non-voluntary actions in the case of State of Kerala vs. Sankaran Nair. The court came to the conclusion that there is never any breach of the prohibition against self-incrimination. The court stated that the order to provide finger impressions or sample handwriting is not against the right under Article 20(3), even in the cases of Gulzhar Khan v. State, Delhi Administration v. Pali Ram, and Kumaran Nair v. Bhargavi. Regarding the right granted by Article 20(3), there have been a number of contradictory rulings. In the State of Bombay vs. Kathikalu Oughad case, specific problems are addressed. They have a connection to:
I.whether Article 20(3) permits police to compare the handwriting of a person who has been accused of a crime;
II.II. A judge may order an accused person in court to provide a sample of his handwriting and signature for comparison under this section. Article 20(3) of the Indian Evidence Act was violated by section 73.
III. III. if it was against Article 20(3) for an investigating officer to take an accused person's palm and finger impressions in front of a magistrate.
By a majority vote, the Court ruled that the framers of the Constitution never intended to obstruct any effective or efficient investigations that could bring offenders to justice, but rather to protect accused individuals from self-incrimination. Additionally, capturing thumb impressions and handwriting is permitted by Section 73 of the Indian Evidence Act and Sections 5 and 6 of the Identification of Prisoners Act. The documents they supply are not considered personal testimony and are not covered by Article 20(3) preview.  Additionally, it was stated that "to be a witness" does not include providing thumb impressions, specimen writings, palm prints, or displaying any bodily part. Finger impressions were being taken even before the Constitution was draughted. It goes without saying that fingerprinting is an infringement on personal freedom. Furthermore, the individual is not providing any personal testimony when he is asked to provide his fingerprints or a sample of his handwriting by a court or other authority. This firsthand account relies on free will. Even if an accused person chooses not to make a statement, he is still required to provide his fingerprints and a sample of his handwriting.
The evidence gathered by forensic investigators proves a person's presence or involvement in a specific location, or even the presence of traces of a certain chemical. The protection provided by Article 20(3) of the Indian Constitution can be taken into consideration when the individual in question is willing to provide his signature and a sample of his handwriting without objecting. Additionally, Article 20(3) does not apply when an accused person is instructed to provide his signature, thumb impressions, footprints, and fingerprints as a witness against himself.  In summary, it is clear that providing an accused person's impressions, writings, or signature does not fall under the definition of "to be a witness," even though it may constitute providing evidence. These fall within the third category of material evidence, which goes beyond the bounds of testimony, but they are neither oral nor documentary evidence. A Few Case Laws Fingerprints were discovered on two glasses at the deceased's house in Ammini v. State of Kerala. The fingerprints of the accused and those of the expert were compared and totalled. However, because they are unclear and it was unclear whether the photos were of the original prints, the Trial Court did not consider this to be a significant piece of evidence. The Supreme Court relied on fingerprint evidence to prove the accused's guilt after the High Court chastised the Trial Court for holding this opinion. The court stated in Balakrishna Das Agarwal v. Radha Devi that a forensic scientist is essentially a court witness, not a witness for the prosecution or defence. It also stated that an expert is a person who expresses his opinion based on his experience, knowledge, and training.
According to the Bhaluka Behra v. State case, the weight and significance assigned to an expert's opinion are two different things. In actuality, a fingerprint is an unforgeable signature. Thus, the fingerprint expert's testimony is likewise accorded a lot of weight.  The Kerala High Court ruled that no two people could have identical fingerprints, even in the Pathumma v. Veerasha case. Even a person's finger impressions vary; no two fingers leave the same mark. We can conclude that they were created by the same person if no differences are discovered.
In the case of James v. State of Kerala, photographs were made of the finger and foot impressions that were taken from the crime scene. However, these images were hazy and rather unclean. However, the Kerala High Court stated that the court has the authority to determine whether or not fingerprints constitute a trustworthy form of evidence, even if they are unclean and blurry.  The Patna High Court stated in State v. Karugope that the fingerprint expert's judgement is recognised and considered a sufficient piece of evidence for the accused's conviction.
Twin Fingerprints and the Principle of Uniqueness

Fingerprints are a universally unique identifier, distinguishing even identical twins. While identical twins share nearly identical DNA, their fingerprints are distinct due to differences in the developmental environment in the womb. Studies by researchers like Jain and Han have confirmed that even with identical twins, fingerprint identification systems can differentiate prints with negligible error rates, demonstrating the individuality of these patterns.

The uniqueness of fingerprints lies in their minutiae—the fine details within the ridges of each pattern. These include features like ridge endings, bifurcations, and dots, collectively referred to as "Galton details." While two individuals may share general patterns like loops, arches, or whorls, the precise arrangement and configuration of minutiae are unique to every individual, making fingerprint identification reliable.

This principle of uniqueness has been a cornerstone of modern forensic science since the 19th century. Early fingerprint identification systems in the United States emphasized this concept, with experts asserting that no two fingerprints are identical, even among large populations. This understanding forms the basis for using fingerprints in law enforcement, forensic investigations, and criminal justice.

Collecting Fingerprints at Crime Scenes

The process of collecting fingerprints at a crime scene involves identifying and analyzing three main types:

1. Latent fingerprints: Invisible to the naked eye, these are created by the natural oils and sweat on the skin. Techniques like dusting with powders (e.g., metallic or fluorescent powders) or chemical methods (e.g., iodine fuming or cyanoacrylate) make these prints visible.
2. Patent fingerprints: Visible prints made by substances like blood, ink, or dirt transferred from the fingertip to a surface.
3. Imprinted fingerprints: Three-dimensional impressions left on soft materials such as wax, tar, or soap.

Specialized tools like the Polylight System and chemical reagents are used to enhance print visibility depending on the surface type.

Analyzing Fingerprint Patterns

Fingerprint patterns fall into three primary categories:

1. Loops: The most common type, forming loop-like shapes. Radial loops point toward the thumb, while ulnar loops point toward the ulna bone.
2. Arches: Characterized by wave-like patterns. Simple arches are smooth, while tented arches form sharp peaks.
3. Whorls: Circular or spiral patterns, sometimes appearing as double loops or unusual shapes.

The surface type influences fingerprint recovery methods. For example, ninhydrin is used on porous surfaces like paper, while powders are effective on non-porous surfaces like glass. Silicone casting is often employed for semi-porous surfaces. The uniqueness and persistence of fingerprints make them invaluable in criminal investigations, identification, and ensuring justice.

Fingerprint Types, Classifications, and Detection Techniques

Types and Classifications of Fingerprints

Friction ridges on the palmar surfaces of hands and feet create unique patterns known as fingerprints. These ridges form intricate designs that differ in length, shape, bifurcations, and twists, resulting in a distinctive fingerprint for each individual.

Fingerprint classification systems help organize these patterns based on morphology:

1. Henry System: Widely used, especially in India, categorizes fingerprints into loops (60–65%), whorls (25–35%), arches (6–7%), and composites (1–2%). Loops can be radial or ulnar, while whorls include spiral, double spiral, and almond shapes. Arches are categorized as plain, tented, or exceptional.
2. Roschler System: Developed in Germany.
3. Vucetich System: Used in South America.

Fingerprint Detection at Crime Scenes

Fingerprints are critical evidence in criminal investigations, as offenders often leave traces on objects they touch. Investigators reconstruct crime scenes and identify points of contact while preserving evidence. Depending on their nature, fingerprints fall into three categories:

• Latent fingerprints: Invisible, revealed through powders, chemical methods, or laser techniques.
• Patent fingerprints: Visible prints made by substances like ink, dirt, or blood.
• Imprinted fingerprints: Three-dimensional impressions on soft materials like wax or soap.

Fingerprint Detection on Porous Paper

Paper poses unique challenges due to its diverse types, compositions, and microstructures. Techniques for fingerprint detection on porous materials include:

1. Physical adsorption: Uses powders and chemical reagents like ninhydrin.
2. Optical methods: Capture fingerprint fluorescence under ultraviolet (UV) light or laser excitation.

Advanced Optical Techniques

Laser-induced fluorescence is particularly effective, using UV lasers to excite trace fingerprint materials, resulting in fluorescence that is captured by photodetectors. Benefits include high sensitivity, resolution, and non-destructiveness.

Detection Methods on Paper

To enhance fingerprint visibility on porous papers like copy paper, newspapers, and sticky notes, scanning electron microscopy (SEM) reveals their fibre-and-filler structure. UV lasers at 266 nm focus on paper surfaces, exciting fingerprint substances to emit detectable fluorescence.

Detection employs two modes:

• Rough detection: Locates fingerprint regions on paper.
• Fine detection: Provides precise fingerprint details.

These methods ensure high-resolution and large-scale fingerprint detection, aiding forensic investigations with quantitative evidence.

CONCLUSION

Fingerprints have proven to be an invaluable tool in forensic science, serving as unique, reliable identifiers for individuals. The distinctiveness of fingerprint patterns, including loops, whorls, and arches, ensures their accuracy in identifying individuals, even in challenging scenarios like distinguishing between identical twins. Classification systems like the Henry System have further refined fingerprint categorization, making them integral to criminal investigations globally. Advancements in detection techniques, especially on porous materials like paper, have significantly enhanced forensic capabilities. Modern methods such as laser-induced fluorescence and optical imaging allow for non-destructive, high-resolution fingerprint detection, even on complex surfaces. By combining physical and biochemical approaches, investigators can preserve and analyze latent fingerprints effectively, yielding critical evidence for solving crimes. In essence, fingerprints serve as "human ID cards," bridging the gap between forensic science and justice. Continued innovations in detection and analysis will only strengthen their role in criminal investigations and identity verification. This enduring reliability underscores the significance of fingerprints as an essential tool in law enforcement and beyond.

REFERENCE

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