Detectives use spatter reconstructions to piece together what a crime might have looked like as it happened. Typically, investigators pin string from blood stains to a possible point of origin, but this method overlooks the fact that blood drops arc through the air. Forensic-surveying engineer Ursula Buck and her team at the University of Bern in Switzerland use laser scanners and imaging software to re-create accurate spatter trajectories. First, digital photographs of the crime scene are stitched into a panorama that shows blood-stain size and location, while the laser scanner creates a 3-D rendering of the room. The mass of each droplet is then calculated based on the size of the stain. Finally, using an algorithm developed by the Swiss team, every drop of blood has its path re-created, no string attached.