Thirty years ago, Cape Girardeau, Missouri, became the hunting ground for a predator. Women were being brutally raped and murdered in a series of savage-and seemingly unconnected-crimes.

Not until 2007 would the truth come to light, when DNA evidence pointed the finger at Timothy Krajcir, a convicted sex offender who'd never even appeared on a suspect list. He was a man who had pursued a degree in criminal justice and psychology-alongside the very investigators who would later use those same criminal sciences to finally stop him.