Dr. Larry Farwell believes he's invented new technology that will revolutionize crimefighting by telling investigators what's inside someone's head. "I'm sort of a neuroscientist by training and a crime fighter almost by happenstance," he says. Dr. Farwell calls his invention brain fingerprinting. It's based on the widely accepted theory that when people are presented with familiar information, like words or images, their brains unconsciously emit special electrical signals called brain waves.