Motives & Murders: Cracking the Case

When 18-year-old Lisa Monza is murdered in San Lorenzo, California, investigators look for a connection to other unsolved crimes in the area, but it will take several years and help from an unlikely source before they can track down her killer.

A respected widow is beaten to death in her Salt Lake City home. Investigators suspect the victim knew her killer, but it will take 20 years before a set of child's fingerprints can put him at the scene of the crime.

A high school senior is murdered in her family's Minnesota farmhouse, but with little evidence the case soon goes cold. Years later, a fresh set of eyes spots an overlooked clue, but cold-case detectives will need more to convict the killer.

In a sleepy New Hampshire town, a man answers a knock at the door and is shot dead through the screen. Investigators are stumped until they uncover a seething grudge and a culprit closer to home than anyone could have imagined.

Deep in southern Louisiana, the bodies start piling up in a series of deadly home invasions. There's a curious link between the victims and a similar MO, and before long, a combined task force is on the hunt for a serial killer.

When the mutilated body of 17-year-old Lori Billingsley is found in a ditch on the outskirts of town, it's obvious a sadistic killer is on the loose in Oregon. When the case goes cold, it's her sister who's determined to get justice for Lori.