3D scanning can now help solve crimes.

Police departments are now using 3D scanning software to create three-dimensional images of crime scenes and evidence. A 3D printer scanner can create casts of footprints and fingerprints, 3D models of car crashes and industrial accidents, and help with facial reconstruction and identification that can help ID victims. Some departments are even using images created by these scanners in court to convict criminals.

Currently, investigating officers must use a painstaking and time-consuming process of taking photographs, putting down reference markers and more. Investigators must make difficult decisions to determine which items to mark, measure, and take into evidence. While police reliably catalogue the most important evidence, such as bullet casings and weapons, they may miss less obvious evidence. Since the yellow crime tape cannot stay up forever, investigators must work hard to detail a crime scene quickly and accurately; rapid prototypes helps law enforcement create scale models quickly and accurately.

How 3D Scanning Works to Solve Crimes

There are two main types of 3D scanning technologies used in forensics. Investigators use one kind to create a large overview map of a crime scene. This type of 3D scanning establishes the relative position of objects but creates rough 3D images of the objects. The second type of 3D scanner creates full color, close-up images in high resolution.

Most 3D scanning equipment uses lasers to measure information in three dimensions. The scanners work by moving a laser dot or stripe across the target. A camera, seated at a slight angle to the laser source, captures the images. The laser dot or stripe will appear at different places in the camera’s field of view depending on how far away an item is from the camera as the laser strikes it.

One of the most important benefits of using 3D scanning tools is that they do not affect the original crime scene or disturb evidence in any way. This is essential for preserving fragile or important forensic samples.

Another advantage to 3D scanning is that it investigators must record images of the crime scene only once, but investigators, legal representatives and jurors can virtually revisit the crime scene as many times as they like. The technique saves a great deal of time, sparing officers from time spent detailing a crime scene. The technology allows users to recreate any existing 3D environment to improve the accuracy of an investigation or help with the prosecution of a suspect. These scans also allow detectives to find and inspect evidence they may have missed during their visits to the crime scene.

To improve accuracy even more, the process allows officers to create a reconstruction without disturbing the original crime scene. Police would no longer have to worry about breaking fragile evidence or making errors in noting the location of important items.

This same 3D technology could also be helpful for filing insurance claims, planning for post-hospitalization aftercare and more.

How Law Enforcement Already Uses 3D Scanning

Originally designed to help UW-Madison’s School of Nursing study homes and health, 3D scanning services are now proving valuable at crime scenes. The Wisconsin Institutes for Discovery researchers who developed the technique hope three-dimensional scanning can improve efficiency at even the most complicated crimes scenes.

To use the scanner, the law enforcement officer sets the scanner on a tripod in the middle of a crime scene. The scanner rotates rapidly for up to 15 minutes, collecting 11 to 45 million data points. The officer would then move the scanner and tripod to a different part of the crime scene environment and collect more data points. Investigators would then stitch the individual scans together in a process known as registration, which creates a cohesive 3D model.

Police can then project the 3D image in a special room known as “The CAVE,” which features walls, a floor and ceiling made of screens. An individual can then walk through the room wearing 3D glasses to get a realist view of the crime scene.

Until law enforcement approached the UW researchers in 2013, the scientists had not considered the usefulness of this technology at crime scenes. Today, the researchers are looking to expand this technology and are currently working with the Dane County Sheriff’s Office to obtain grants to continue development.

3D Scanning in Other Police Departments

Several police departments have begun to use similar scanners to detail crime scenes. Police in Roswell, New Mexico, use a scanner that uploads the stitched images to a computer, rather than projecting the results onto a wall. Investigators can take measurements and mark specific evidence with only an iPad.

Another type of 3D scanning is now helping convict criminals overseas. In April 2015, investigators in England used 3D scanning to convict a man. In that case, experts used 3D scanning technology to create images of the evidence that were 43,000 times more detailed than a hospital CT scan. Using this technology, the prosecutors were able to associate marks on the victim with tools used by the criminal. The case marks the first time a UK force used 3D scanning to solve and prosecute crimes.

The maker of the scanners is now teaming with law enforcement there to solve several other crimes. While mainly used for traffic incidence, the technology can create images from more severe crimes. The software can calculate bullet trajectories, determine a person’s height, and even features blood splatter analysis.

The technology, created by the American company FARO, can create images showing the perspective of the victim and the offender. These images may be projected in a courtroom for the jury to examine. Image creation is fast, with each part of a crime scene taking only five and a half minutes to record.

Guilford County Sheriff’s Office in North Carolina also uses 3D scanning by FARO to create panoramic images of crime scenes. Officers in this department have used the technology in several investigations because of the way it provides visual evidence.

“Juries and even the attorneys, the DA’s and the defense attorneys, everybody tends to be visual,” said Sgt. Patricia Wisneski. “So while you’re trying to explain how something was and you take photos and even do video, it’s different when you actually see a perspective where you’ve actually got the measurements.”