Caril Ann Fugate and Charles Starkweather
From Wikipedia on Caril Ann Fugate
"Fugate lived in Lincoln, Nebraska, and in 1956 she started dating Charles Starkweather. He was five years her senior, a dropout, and a truck unloader at the Western Newspaper Union warehouse.
On January 21, 1958, Fugate later claimed to have come home to find that Starkweather had shot Marion Bartlett, her stepfather, and her mother Velda to death. Fugate made lunch while Starkweather choked and stabbed her baby half-sister Betty Jean to death. (Starkweather, on the other hand, claimed that she had been in the home during all three murders.)
During the next seven days, the pair lived in the house with the bodies and turned away all visitors, which made Fugate's relatives suspicious. Starkweather and Fugate then fled, driving across Nebraska on a spree of robberies and murders that claimed seven more lives before they were arrested.
Fugate's downfall was admitting to holding a .410 shotgun on a young high school couple in a car while robbing them of $4.00. The couple were shot and killed later that evening. The girl was found partially naked, and she was brutally stabbed multiple times in the abdomen after being shot.
Starkweather and Fugate accused each other of the girl's murder. Starkweather admitted to killing the boy."