Weapons are the hallmark of violent crime, tools designed to harm - or kill. Forensic science has developed a world of techniques for tracking and identifying these devices. Blood spatter, explosive residue, ballistics and trauma wounds tell crime scene investigators their deadly story.

Can the sound of a suspect's voice reveal his lie? Can the crucial moment of crime, buried deep in damaged video, be revealed? Can computers isolate a guilty face in a crowd? No longer science fiction, these are the high-tech tools of the forensics trade.