S13·E45 Watchful Eye

On May 20, 2001, 20-year-old state park employee Carrie Nelson was beaten to death in the park office while working alone in the middle of the afternoon. There’s a wealth of evidence at the scene, but it doesn’t implicate the prime suspect, it clears him. Six years -- and 600 leads -- later, advances in DNA technology enable investigators to identify and convict the killer.