Manuela Allen went to bed in July 2019, but by the morning, she was gone. Blood splatters in her bedroom suggested the teacher had been the victim of a brutal crime.

Eugene Mallove was a beloved family man and an accomplished scientist who had come down to Norwich, Connecticut to clean a home he'd been renting out when he was viciously murdered.

It would take more than three decades for investigators to learn who shot Barbara Rocky, a 1974 Brigham Young University student, to death in Big Cottonwood Canyon. 

Patricia Kimmi vanished in November 2009, but investigators suspected foul play after discovering her dentures, a money clip covered in blood, and bloody coins not far from her Kansas home.