Motives & Murders: Cracking the Case

When 18-year-old Lisa Monza is murdered in San Lorenzo, Calif., investigators look for a connection to other unsolved murders in the area.

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

A high school senior is murdered in her family's Minnesota farmhouse, but 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.

A New Hampshire man is shot dead through his screen door; investigators are stumped until they uncover a seething grudge and a culprit closer to home than anyone could have imagined.

In southern Louisiana, a task force forms to hunt for a serial killer following a series of deadly home invasions.

The mutilated body of 17-year-old Lori Billingsley is found in a ditch on the outskirts of town, pointing to a sadistic killer on the loose in Oregon, but Billingsley's case goes cold, and it's up to her sister to pursue justice.