The Proof is in Your Fingerprint

From ancient Babylon to modern forensics, fingerprints have been the gold standard of identification—now sharper than ever with AI and advanced technology.

You might be surprised to know how your fingerprints reveal more than you think. It is one of the most distinctive and trustworthy techniques of identification. A fingerprint is a mark made on surfaces by the tips of our fingers whenever they come into contact. Interestingly, each person—even identical twins—has a unique fingerprint pattern. Loops, whorls, and arches are the three main designs. Fingerprints are divided into three categories according to their visibility. Latent prints, which are not apparent to the human eye, are frequently discovered on materials including glass, plastic, and paper. When fingers get stained with paint, blood, or dirt, visible patent prints form. Three-dimensional impressions created on pliable materials like clay, wax, or wet paint are known as plastic prints.

Fingerprints can be found on various surfaces, including metal, wood, human skin, clothing, weapons, doorknobs, car steering wheels, mobile phones, old letters, and paper. They can be made visible using different techniques, depending on the type of print and the surface. One common method is powder dusting, which involves applying special fingerprint powders (black, white, or brightly coloured) and lifting the prints with tape. Chemical methods such as ninhydrin and DFO (1,2-diazafluoren-9-one) are used to develop latent prints, while super glue fuming, iodine fuming, and silver nitrate techniques are also effective. Additionally, ultraviolet (UV) or coloured light sources can reveal hidden prints.

Fingerprints have been used for identification since ancient times. In Jericho (circa 7000 BC), thumbprints of bricklayers were discovered, while in Babylon (1955–1913 BC), fingerprints were used to seal contracts. However, modern scientific applications began in the late 19th century. Sir Francis Galton’s 1892 study on fingerprint patterns established their uniqueness and permanence. Sir Edward Henry’s 1897 Henry Classification System organised fingerprints for comparison. The first bureau in India was established in Shimla in 1901. Dactylography is a Greek term that means finger writing, and dactyloscopy is to view the finger's fingerprint.

Fingerprint analysis has been recognised as a biometric technique in forensic science by the Supreme Court of India. One such example is the “Nithari Killings” (2006), in which the defendant is linked to multiple killings via fingerprint evidence. In notable cases like O.J. Simpson’s and State of U.P. vs. Rajesh Gautam (2003) and JonBenét Ramsey Case (1996), the admissibility of fingerprint evidence was upheld, highlighting its scientific reliability and uniqueness. Other examples include the Aarushi Talwar Murder Case (2008), the 1892 case of Francisca Rojas in Argentina, and the Nirbhaya Case (2012).

Researchers are exploring innovative imaging techniques like ultraviolet and infrared light to capture latent fingerprints, enabling forensic experts to recover previously unrecoverable prints. Artificial intelligence (AI) is increasingly getting integrated into fingerprint analysis systems, enhancing accuracy and reducing human error. The aim is to strengthen defences against spoofing and forgery. Technologies like AFIS – Automated Fingerprint Information System stores and compares fingerprints. FACTS (Forensic Anthropological and Crime-detection Techniques Simulation) trains students and professionals in evidence collection, skeletal analysis, and scene reconstruction. Multimodal biometric systems, integrating fingerprint recognition with facial recognition or iris scanning, are being researched. Universities like IIT are using digital tools and latent enhancement techniques to improve detection methods and reduce human error. Moreover, researchers are exploring the use of machine learning algorithms to analyse fingerprint patterns more efficiently and accurately than traditional methods.

Dr. Henry Lee and Tirath Das Dogra are leading scientists in fingerprint analysis, focusing on recovering latent fingerprints in challenging environments. R.K. Shukla, Dr. S.K. Sinha, Director of the Forensic Science Laboratory in Ranchi, Jharkhand. Dr. M.P.S. Sengar is associated with the CFSL, Hyderabad, in fingerprint analysis and crime scene investigation. Their work has significantly contributed to linking suspects to crime scenes through fingerprint evidence.

In today's world, where technology is rapidly evolving, fingerprint analysis remains a cornerstone of forensic science. Its reliability, uniqueness, and adaptability make it an invaluable tool in criminal investigations and identity verification. As AI and advanced imaging techniques continue to refine fingerprint detection and analysis, the future promises even greater precision and efficiency. From ancient Babylonian contracts to modern-day courtrooms, fingerprints have stood the test of time—proving that even the smallest details can leave the biggest impact.

(Dr. Kumar is a retired IPS officer and forensic consultant to the Assam government. Phukan is a student of National Forensic University, Guwahati.)