Laser Scanning Preserves Evidence

Newer to the forensics field is 3D laser scanning technology. These tools allow analysts to collect precise dimensions, blur moving face in video evidence and features to be recorded for later analysis. By capturing large amounts of data very quickly, 3D laser scanners allow investigators to capture a complete 360-degree image of a scene in minutes. The Trimble TX8 3D laser scanner, for example, captures up to 1 million points per second and can perform a typical high-density scan in about three minutes. " In a traditional crime scene, investigators identify all the evidence in the environment," Cognitech says. "Some evidence is tangible such as a gun or a knife, while other evidence is residual, like blood, fluid and footprints software to measure distances in image The challenge is you don't always know the value of what's on your scene until later. With 3D laser scanners, you are measuring and documenting absolutely everything, so your entire scene is preserved exactly as it was." Scanning variables include the density settings of the scanner and the distance from the item. A small drop of blood on a wall may or may not have a scan point depending on these variables. "If documenting them precisely is important, then the technician will make sure the density settings are high and the area is scanned from different positions/angles," Cognitech explains. "Also, scanners use cameras to colorize scans when light is available, but light is not required to scan items." Part of the value of bringing 3D scanning to crime and crash investigations is the fact that evidence can be documented, analyzed and processed later, as needed, enabling investigators to more quickly clear the scene same picture different perspective. This might happen if new evidence surfaces or if suspects change their stories. Until recently, 3D scanners had been slow to be adopted by forensics teams, mostly because resources are tight for law enforcement agencies and many already invested in their total stations, according to Cognitech. The Wisconsin State Patrol Technical Reconstruction Unit, for instance, currently provides forensics mapping expertise to 72 counties across the state with 17 robotic total stations, six GNSS rovers, and only three 3D laser scanners. That means Cognitech and his team must shuffle laser scanning equipment and manpower across the state at a moment's notice.