3D fingerprints: The latest tool in the crime fighting arsenal

On February 8, 1942, Chief Superintendent Frederick Cherril from Scotland Yard was called to an air raid shelter in London, where the body of a 40-year-old pharmacist, Everlyn Hamilton, was found in the gutter.

Cherrill was brilliant at his work; he was a pioneer and palm print expert who had already played a significant role in the evolution of fingerprint forensics. His trademark? He was said to be able to identify single fingerprints at the crime scene, a difficult task back then.

Cherrill and Detective Sydney Birch initially suspected that Hamilton was a victim of theft, as her handbag was missing and she had been strangled. There were no signs of mutilation. A closer look at the pattern of bruises revealed that Hamilton's killer was left-handed.

Hamilton was the first victim of a man who later became known as the infamous Blackout Ripper. Twenty-seven-year-old Gordon Frederick Cummins unleashed his reign of terror 54 years after the notorious killer Jack the Ripper preyed on unsuspecting women.

Cummins' second murder left the first real clue. Evelyn Oatley, a thirty-five-year-old prostitute, had been strangled in her apartment, and Cummins had used curling tongs and a can opener to mutilate the victim's body. Cherill uncovered the first clue to the killer using his unique skills - a single fingerprint on one of the instruments.

The ultimate crime-fighting tool. Once upon a time.

The third murder saw more prints found on a candle that had been inserted inside the victim, matching prints left at the first two crime scenes.

Back then, fingerprint matching was primarily used to find matches with suspected felons who may have committed previous crimes and had been involved in the court process. The science was complex - over one thousand permutations of finger and palm prints had to be stored and cross-referenced.

Unfortunately for the investigators, Cummins was not a previous felon, and no fingerprint records were on file to identify him as the killer.

In his later murders, he left behind a belt and a service respirator that bore the serial number 525987, which was used to track his identity. Though tracking the owner of these objects was prioritized in the search for the killer, the fingerprints would eventually help the jury decide — which took just 35 minutes.

Tracing the origin

The science of fingerprints made its debut in Calcutta (now Kolkata), India, more than a century ago.

In June 1897, the world's first official Fingerprints Bureau was established in Calcutta, mainly due to the efforts of three men - then police chief of south Bengal, Sir Edward Richard Henry, Khan Bahadur Azizul Haque, and Rai Bahadur Hemchandra Bose.

They started maintaining criminal records using a method for indexing and classifying fingerprint patterns, known as the “Henry Classification System".

Two months later, on August 16, 1897, Hridaynath Ghosh, manager of Kathalguri Tea Estate (now Jalpaiguri district) in West Bengal, was found brutally murdered in his bungalow, his throat slit open. His former domestic helper, Ranjan Singh, alias 'Kangali', was a top suspect. Kangali had previously served a six-month prison term for theft.

Kangali's bloody fingerprints were found at the scene, linking him to the murder. That was considered the first time that a crime was detected using fingerprints.

A few years later, in 1901, Scotland Yard established its first Fingerprint Bureau. In 1902, the New York police and state prisons adopted the use of fingerprints, followed later by the FBI.

Not just an old detective's trick

Since then, fingerprints and related technology have evolved and played a crucial role in solving even decades-old cases. In the 1980s, the Automated Fingerprint Identification System (AFIS) helped law enforcement officials classify, search for, and match fingerprints, enabling them to cross-check a print with millions of fingerprint records rapidly.

The introduction of Integrated AFIS (IAFIS) in 1999 took fingerprint identification a step further. Maintained by the FBI's Criminal Justice Information Services Division, the system can categorize, search and retrieve fingerprints from virtually anywhere in the country in as little as 30 minutes.

IAFIS allows local, state, and federal law enforcement agencies access to the same vast database of information and collects fingerprints for employment, licenses, and social services programs (such as homeless shelters).

But, in general, the science of fingerprints has been virtually unchanged since its debut.

Most fingerprints are two-dimensional, and an image of a fingerprint may not deliver a crystal-clear picture. In some cases, this can make it challenging to find perpetrators. 

Enter Akhlesh Lakhtakia, Evan Pugh University Professor, and Charles G. Binder, Professor of Engineering Science and Mechanics.

The immense potential for 3D fingerprints

Earlier this year, Lakhtakia received a $300,000 grant from the Criminal Investigations and Network Analysis Center to explore a technique for creating 3D holograms of fingerprints. The grant will support two years of research in collaboration with researchers at the University of Dayton.

“Why store fingerprints as 2D objects?” Lakhtakia says.

“When you impress your fingers on a surface, the print you leave behind is a three-dimensional object. It’s a ridge-and-valley structure with sebaceous ridges about a tenth of a millimeter tall. So why are we throwing away the potential of the third dimension?”

"The potential of 3D fingerprints has existed for a long time, but the real issue was the expense involved. To some extent, that has been resolved, through digital holograms themselves. However, the primary problem that arises is the question of whether 3D holograms of fingerprints can be done under realistic circumstances," Lakhtakia tells IE in a video interview.

'Chemically potent material' that can be affected by degradation

Fingerprints are left on various surfaces- ranging from the blade of a knife to walls, window panes, and garbage bags. And usually, when crimes are committed, blood is involved.

"Blood congeals, and though it is easy to see a fingerprint in blood, the entire print may not have blood on it. Most of the time it is these partial bloody fingerprints that are left behind, that are difficult to develop, to process, and to determine who they belong to," Lakhtakia says.

Typically, fingerprints are collected days, months, and even in some notable cases, years later. This means that they have undergone environmental degradation and are exposed to various conditions.

"These factors are inimical to the preservation of the fingerprint, which is a residue that has water, lipids, and some salts in it. The print is a chemically potent material that can be acted upon by environmental conditions," he says.

Capturing level 3 features

Creating 3D holograms of fingerprints can better identify and capture features that usually cannot be captured through traditional processes.

"The pores in your prints are specific and central to the situation, even in partial fingerprints," Lakhtakia says.

He brings up the Madrid train bombings in 2004, in which an American lawyer, Brandon Mayfield, was wrongfully detained based on a faulty fingerprint match.

"The real perpetrator was found a few weeks later. But what had happened was that a partial fingerprint of one person was muddled with a partial fingerprint of another person," Lakhtakia says.

Therefore, it is crucial to examine the more intricate features present even in partial fingerprints. Those features, such as pores, are referred to as level 3 features in forensic lingo, Lakhtakia says, adding that "Level 3 features are generally not captured by 2D fingerprints."

How does it work?

For the 3D image, the team will deposit fingerprints on different materials, like glass and wood. The fingerprints for each material will be aged under various environmental conditions, such as different temperatures and levels of humidity, for different periods.

The researchers will then brush the fingerprint with a very thin metal layer in a method previously developed by Lakhtakia and his collaborators. This metal layer will preserve the fingerprint pattern so the pattern can withstand the energy from an optical laser scan.

The fingerprints will be sent to Partha Banerjee’s lab to make digital holograms, which can be stored and reconstructed in 3D on a computer. Banerjee, an electro-optics and photonics professor, leads the fingerprint study at the University of Dayton.

"It can change the whole nature of the game," Lakhtakia says.

What's next?

The Department of Homeland Security funds Lakhtakia's work.

"3D will be the new protocol for fingerprint analysis in the near future. That is why the U.S. Department of Homeland Security is so interested in this work," Banerjee told the University of Dayton News.

"Eventually, when they see scientific and forensic merit, the U.S. Department of Homeland Security could start funding a different kind of research - find companies to come up with simple equipment for the same," Lakhtakia tells me.

The Miami Valley Crime Lab will grade the quality of the fingerprints captured by Penn State and the University of Dayton's 3D reconstruction from holograms.

Though 3D hologram fingerprints could be a game-changer, it has implications that aren't restricted to identifying perpetrators in the criminal justice system. It also has immense potential for background checks, and biometrics and can improve other processes that require prints.