Jul 21, 2016 | By Benedict

Anil Jain, a professor at Michigan State University, has made 3D printed replicas of a dead man’s fingers in order to aid police investing the man’s murder. The police hope that the 3D printed fingers can be used to unlock the victim’s smartphone, which uses a fingerprint recognition lock.

Prof. Anil Jain

It sounds like the plot of a Hollywood crime movie: detectives investigating a murder believe that important clues can be found on a victim’s smartphone, but that smartphone can only be unlocked with the touch of the victim’s fingers. Not having this option, the detectives turn to a mysterious technology which can create new copies of those fingers, which can push the sensors to unlock the secrets of the crime. It sounds bizarre, but the technology in question here is actually something we’re all familiar with: 3D printing. When officers investigating a murder approached MSU’s Anil Jain last month, they hoped he would be able to achieve the unusual goal of creating fake fingers, by using a 3D printer and data from fingerprint scans collected years before.

Jain, a computer science professor, has years of experience in facial recognition programs, fingerprint scanners, and other biometric identifiers. Because of this experience, the police believed the professor could assist the murder case by 3D printing realistic replicas of the dead man’s fingers. While the police could have asked the manufacturers of the phone to unlock it digitally, they decided that the unusual 3D printing route could be faster and less complicated—Apple, after all, famously refused to supply the FBI with access to the iPhone of the San Bernadino shooter in February, prompting a worldwide discussion on technological security.

Fortunately for Jain and the police, the victim’s fingerprints were already on record, since he himself had committed a crime years before. Using those scans, Jain’s PhD student Sunpreet Arora was able create 3D printed replicas of all 10 digits, potentially enabling the police department to finally unlock the smartphone. “We don’t know which finger the suspect used,” Arora told Fusion. “We think it’s going to be the thumb or index finger—that’s what most people use—but we have all ten.”

Smartphone fingerprint technology / Image: Phone Arena

Although already a complicated process, there were further aspects that Jain and Arora needed to consider before their 3D printed fingers had a chance of unlocking the smartphone. To prevent this kind of trickery from actually working, phone manufacturers generally make their fingerprint readers capacitative, meaning that tiny electrical circuits must be closed for the fingerprint to be recognized as a real finger. While skin is sufficiently conductive to activate the sensors, ABS, PLA, and typical 3D printing materials are not. Because of this, Arora needed to coat the 3D printed fingers in a thin layer of metallic particles.

Jain and Arora are still testing the coated 3D printed fingers to determine if they could activate the fingerprint recognition function of the victim’s smartphone. In a few weeks, once further testing has been completed, Arora will hand the finished fingers to the police, who will attempt to unlock the encrypted device and collect further evidence.

While 3D printing replica fingers is not yet common practice, additive manufacturing has been used in various other ways to assist police and the legal system. Earlier this year, a British prosecutor created several 3D printed skulls for the Ellie Butler murder trial. Ben Butler, father of six-year-old Ellie Butler, was on trial for his daughter’s murder, and was eventually jailed for life in June after being found guilty. The 3D printed skulls were presented to the jury to demonstrate the extent of Ellie Butler’s injuries upon her death. During the trial, the defense attempted to play down the reliability of the 3D printed replicas, the barrister opining that “too much reliance should not be placed on their absolute accuracy.”

3D printed skulls used in Ellie Butler murder trial

Other uses for 3D printing in criminal investigations include 3D printed replicas of crime scenes. Using advanced 3D scanning technology, police departments are now able to digitally map entire crime scenes in 3D. These 3D scans can then be closely examined on computer screens, or turned into 3D printed models for physical inspection. In January, police used such a 3D printed model to defend the police officer who shot and killed 12-year-old Tamir Rice, a black Cleveland youth who was carrying a toy gun.



Posted in 3D Printing Application



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