The law enforcement officials working the murder case of Ellie Butler were concerned that they were about to hit a bump in the road.

Their case would live or die based on whether or not they could establish beyond doubt that the head injuries Ellie had sustained had been dealt by her father, Ben. Problem was, the same injuries could have been caused by a bad fall after jumping off her bed. That was the defense’s stance, six-year-old girls can easily experience such tragic mishaps, after all.

Of course, it was unlikely that injuries as catastrophic as Ellie’s would result from a simple fall, but the doubt raised was enough to jeopardize the prosecution.

Investigators had a potential murder weapon and a motive—Ben Butler’s history of violence—but no means of tying them together. What they needed was a way to reconstruct the moment of the murder itself. More practically, they needed a way of showing what the murder weapon in question could do.

So, after traditional forensic techniques proved inconclusive, the prosecution turned to 3D printing. Digital CT scan and X-ray data of Ellie’s remains were collated and used to produce two 3D-printed replicas of her skull. With them, the pathologist was able to determine the full circumstances of the assault, from the number of participants to the nature of the weapon used.

A high-detail replica skull produced with stereolithography 3D printing. (Illustration)

The abrasions on the 3D printed skull replica suggested that the weapon used had “two geometrically distinct surfaces”—a match to the claw hammer found at the scene and admitted into evidence.

With this case, digital technologies and 3D printing helped solve a crime the first time and a new standard of thoroughness in forensic investigation was established.

Real-Life CSI: 3D Printing in Crime Investigation

3D printing creates three-dimensional parts from computer-aided design (CAD) models by successively adding material layer by layer until the physical part is created.

While these technologies used to be complex and expensive, today’s professional, low-cost desktop and benchtop 3D printers are used for a wide variety of applications and support businesses in various industries including engineering, manufacturing, dentistry, healthcare, education, entertainment, jewelry, and audiology.

Law enforcement and forensic departments around the world are starting to appreciate the power of 3D printing techniques to help solve crimes.

One of the principal virtues of 3D printing is that it allows investigators to recreate models of crime scenes. Not only can the technology accurately represent the dimensions of a four-square room (using millions of data points following a 15-minute scan), but it can precisely remodel much more irregular scenes, spaces, and shapes, too—like car crashes, footprints, and fingerprints.

There is no shape too irregular for 3D printing to handle. In the case of Ellie Butler’s murder, 3D printing was used to replicate complex bone formations.

The National Institute of Justice in the US, one of the foremost developers of 3D printing for forensic use has even printed “phantoms” that can potentially replicate the complex bodily positions of victims. Imagine an entire crime scene faithfully reproduced using 3D-printed models of victims, positioned exactly as they were at the time of the incident.

Even faces can be reproduced. In 2016, Ohio State University partnered with local law enforcement to investigate the provenance of a woman’s body found decomposing in the woods near the town of Dayton. First, investigators turned to traditional facial-reconstruction techniques, but the practice damaged some of what remained of the skull and left little with which to discern the victim’s facial geography.

With their prime evidence badly damaged and decayed for regular reconstruction, the Dayton law enforcement turned to digital technologies. CT scanning and 3D printing helped build a reconstituted image of the victim’s face, one that was so lifelike it was used to positively ID her. The Ohio cold case had suddenly warmed up. The victim had a name: Tiffany Dawn Chambers, a Florida native.

The process of reconstructing Tiffany Chambers’s face based on a 3D printed model of the victim’s skull.

Shortly after suspects were charged and convicted with remarkable speed. Hannah M. Whitman and Prentiss R. Hare were found guilty of “knowingly and willingly participating in the killing of the victim with prior calculation and design, and then assisting in disposing of the body.”

3D printing can also assist in solving crimes at scale. In the 2015 shooting and bombing attack in San Bernardino, California, the technology was used to “to reconstruct multiple scenes for omni-directional context and fallout analysis.”

The Suitcase Killer

In a dismal corner of Birmingham, England, police discovered the charred remains of a corpse, cut up and distributed in two suitcases, which were weighted with rocks so that they would sink in a shallow local river. This was 2015, and, in short course, a man named Lorenzo Simon was accused of murdering Michael Spalding, his tenant (the man in the suitcase). The police suspected that Simon had used a saw to dismember Spalding’s body and he then burned it before sinking remains—mostly ashes and bones—into the river.

Police had considerable grounds for suspecting Simon’s guilt, and his girlfriend’s complicity, but the evidence wasn’t strong enough — it was too degraded. Once again, the thoroughness of a murderer looked as though it would be rewarded with freedom and a jaunty sobriquet: “The Suitcase Killer.”

That is until the West Midlands Police turned to experts at the University of Warwick’s manufacturing department (WMG).

The detectives analysed the digital scans of the bones to match the injuries to the murder weapon.

WMG’s engineers took a fragment of Spalding’s humerus bone, found inside the furnace, and used digital scans to prove that it fit like a puzzle piece with a limb found in one of the suitcases. The advanced 3D scanning techniques used by the researchers also proved that laceration patterns visible on the victim’s bone came from a saw with an identical profile to the one found.

Anatomical models of bones can be used for demonstrative purposes in court. (Illustration)

Justice lay in these fine details, and by revealing them, scanning and 3D printing had carried the murder case from a position of disadvantage to the precipice of conviction. Without it, justice would not have been served to the Suitcase Killer.

The Other Side of Crime

Of course, such powerful technology could not be confined only to the side of the well-intentioned. Criminals have 3D printers too, and a great deal of effort is being expended by the likes of the National Institute of Justice to stop the power of additive technology from being used for nefarious purposes.

In theory, anything produced by a 3D printer is difficult to trace—and of course, almost anything can be produced by these means.

But while the potential misuses of 3D printing are a concern, investigators of criminal use of 3D printing technology are preparing for this challenge with their own innovative technologies from identifying digital files that potentially could be used for illegal activities to tracing chemicals in the plastics used in a 3D printed object to identify the possible printers that made it.

Explore 25 (Unexpected) 3D Printing Use Cases

Luckily, the majority of 3D printing applications have nothing to do with criminal activities. In fact, it’s safe to say that if your day-to-day life hasn’t been touched by 3D printing yet, it soon will be.

It may change your car, your trip to the dentist, your jewelry collection, and the way you run, listen to music, and shave, and more.