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.
"My whole world changed," Laurie Stout's sister said of the moment she learned her big sister was dead. "I no longer had my confidante and no longer had my best friend. It was horrible."
Joseph Wellnitz, his wife, Beth, and 20-year-old son Dennis were all found shot to death in the family's Columbia, Kentucky home in 1993, but it would take investigators nearly a decade to find the surprising killer.
Omar Hernandez, a married father of two, was leaving for the graveyard shift at a local grocery store on October 9, 2016 when he was suddenly ambushed outside his home and shot.
Nicole VanderHeyden and her boyfriend, Doug Dietrie, were out with friends when they got in a huge fight and she stormed off. The next morning, her body was found brutalized in a field.
Jackie and Carl Gaimari had an untraditional but loving relationship when two burglars killed him in 1979. But 30 years later, her sister helped police prove there was more to the story.
When Florida grandmother Ann Trexler got mad that her daughter, Tina, might lose custody of her beloved grandchild, she worked with her hairdresser's boyfriend, Tony Perez, to make sure her former son-in-law could never go back to court.
When a Minnesota mom, Linda Jensen, was found brutally strangled and stabbed in her own bedroom, police had no viable suspects until a tip came in eight years later.
When Gonzalo Pizano-Guzman was found dead in a ditch and his car was burned, no one could understand why someone would want a happy, hard-working young man dead months before his wedding.
When Terri Brooks' brutalized body was found on the floor of her locked workplace on a winter morning in 1984, her family was devastated and her town was terrified that there was a robber killing women at their jobs.