For crime scene investigators, collecting the evidence on a scene is just one part of the challenge. Professionals must also be able to obtain and relate the idea of perspective, especially when there is more to the story than the physical evidence reveals. And there is no better way to convey perspective than with high-definition 3D laser scanning technology and 3D visualization software.
“One of the best things that we can use this [Leica ScanStation technology] for is creating perspective views,” said CSI Section Supervisor Ryan Rezzelle, of the Johnson County Sheriff’s Office Criminalistics Laboratory in Olathe, Kan.
Rezzelle relates one case in which perspective gave the county’s district attorney the information needed to determine charges after a fistfight turned lethal. It began when a fight broke out between two male passengers of a moving vehicle. The driver stopped the vehicle along the side of a highway, and the fistfight spilled onto the roadside. The men eventually tumbled down a hill, and when they reached the bottom, one was dead.
In this case, the physical evidence found at the scene did not provide additional information. “If we were to fingerprint the inside of the car,” Rezzelle said, “it wouldn’t have been of value because we already knew everyone who was in the car. When we looked at the bloodstains, we saw evidence that there was a fight in the car. While bloodstains have strong reconstructive value, in this instance, it wasn’t going to yield what happened during that event.” The only information the CSI team could relate to the district attorney’s office, he explained, was the distance the men traveled down the hill and the angle of the slope. The key was conveying the information in a way that allowed viewers to see the slope and the distance in the proper spatial relationship.
Viewing the Scene in 3D
In the past, the CSI team would try to convey these spatial relationships through 2D work products based upon data collected with tape measures and Rolatapes. “Historically, if we were to present that crime scene,” Rezzelle said, “you’d be looking at a bird’s-eye view where you don’t get the sense of that slope.” Since the CSI team’s transition to laser scanning technology in 2011, they are now able to collect millions of highly accurate measurements with the push of a button, upload the data into Leica Cyclone 3D point cloud processing software to generate interactive 3D work products, and share these perspectives using Leica TruView 3D visualization software.
That was the process Rezzelle and his team used in the fistfight case. “We were able to create a snapshot perspective view from the side,” Rezzelle said, “and see very clearly the distance they traveled and the vertical distance—the drop that occurred over the distance of that run.” In addition to the 3D side-view cutaway, Rezzelle was also able to provide a TruView of the site, which is a more natural viewing medium to which people can easily relate. “When we’re able to display it in both two and three dimensions,” Rezzelle said, “you get much more of a feel for the texture of that scene, the placement of items, and the spatial relationship of them to each other.”
Showing the Truth in the Courtroom
In the end, charges were not filed due to the circumstances of the case. And the perspective provided by the free TruView software in the courtroom was key. “Ultimately, it was one of the exhibits they used in evaluating how they were going to charge the case,” Rezzelle said.
“Fingerprints and bloodstains wouldn’t have been of any consequence because we knew that we had these two guys fighting. But depicting the path and the slope and the distance traveled that they would’ve made going down that hill—that was a valuable tool for our district attorney’s office.”
For more information about high-definition 3D laser scanning solutions for law enforcement and crime scene investigation, contact us.
About the author: Wendy Lyons is journalist living in Canton, Georgia, who spent several years writing about surveying technology for POB magazine. She now focuses on covering laser scanning and other geospatial measurement solutions for public safety professionals.