Erica Hayes says she had an idyllic childhood with her mother and stepfather in a small farming community in Missouri.

Hayes recalls that childhood fondly, but now she has to reconcile those memories with the fact that the people responsible for her upbringing were charged with murdering their ex-spouses decades ago.

In an interview with People magazine, Hayes, now 41, recalls the moment that 71-year-old Gerald Uden, her stepfather, admitted to her that he'd fatally shot his ex-wife, 32-year-old Virginia Uden, and the woman's two children, Richard, 12, and Reagan, 10.

"She says that he asked her what difference would it make if she knew, and she told him it would give her peace," People magazine writer Raha Lewis told ABC News. "And [she said] that he finally confessed to her."

The killings happened in 1980. Uden was arrested in September at the Chadwick home he shared with his wife. He pleaded guilty to three counts of first-degree murder and was sentenced in November to life in prison. In court, he said Virginia Uden had become "intolerable." The bodies of the slain woman and children were never found.

Elderly Missouri Couple Accused of Decades-Old Wyoming Homicides

Hayes' mother, Alice Uden, 74, was also arrested in September on a completely separate murder charge. Authorities allege that Uden killed her ex-husband, 25-year-old Ronald Holtz, by shooting him in the back of the head in late 1974 or early 1975.

The man's remains were found in an abandoned mine.

Alice Uden has pleaded not guilty to a first-degree murder charge.

Both cases happened in Wyoming, and the couple was extradited to that state. Authorities have not speculated whether the crimes are linked beyond the fact that the alleged perpetrators have been married for more than 30 years.

Gerald Uden married Virginia Uden in 1974.

Uden raised Hayes since she was 4 years old, and she said her stepfather's past shocked her.

Her mother's alleged past didn't take her so much by surprise, she said. Hayes acknowledged that she always had a feeling that her mother was hiding something from her.

"Erica told us that, despite everything that happened, her stepfather gave her the most beautiful life he possibly could," said Lewis. "She told us she sees this as a warped love story, one where her mother killed to protect herself and her father killed to be with her mother."

The Associated Press contributed to this report.