Relatives of Lyle and Erik Menendez spoke in an interview Wednesday about their long-running fears that the brothers had been abused for years before they killed their parents.

After a press conference in which they’d called for the imprisoned siblings’ freedom, the family members told Chris Cuomo on NewsNation about how their suspicions only deepened as time passed.

“Over the years we really did know that there was abuse at gut-level. But as time goes on and we all talked to each other more and more, it validates the fears and the gut-level reactions that we had,” the brothers’ cousin Karen VanderMolen-Copley told Cuomo. “That solidified the knowledge that the sexual abuse actually did occur, because that’s not something you want to believe, and then once you talk to each other it becomes more and more obvious.”

Lyle and Erik were convicted of the 1989 fatal shooting of their parents José and Kitty Menendez at the family’s Beverly Hills mansion when the brothers were 21 and 18. They have spent the past 35 years behind bars, but have said all along they were motivated by their father’s physical, emotional, and sexual abuse—which allegedly began when they were children—and by their mother’s silence and complicity.

The prosecution in the case, however, argued the abuse was a “total fabrication.” The brothers just wanted to inherit the family’s multi-million-dollar estate, the prosecution said, as evidenced by the fact they went shopping in the days after the killing instead of turning themselves in.

The jury apparently agreed, returning a murder verdict with a sentence of life in prison without possibility of parole. But now the Los Angeles District Attorney’s office is currently reviewing new evidence the brothers were in fact abused—a circumstance the family believes explains the brothers’ behavior both during and after the killing, they told Cuomo.

“If you look at how much pain they endured, how much torture they endured, how much abuse that they survived through, that came out in the way that they committed the act,” cousin Tamara Goodell said.

Describing the violent killing and its aftermath as “learned behavior,” she continued: “When I think about it now, it’s an act out of pain, it’s an act out of misery, and it’s something that they were just so desperately wanting to get out of.”

Kitty’s sister Joan VanderMolen said she couldn’t explain why Kitty would stay silent while her sons were being abused, except that perhaps her sister had been influenced by her husband and his wealth.

“When we finally realized the depth of the awful treatment [Erik] was getting from his father, and then [Kitty] admitting she knew all along ... it’s beyond anything we can even describe right now because it’s so painful,” VanderMolen told Cuomo, adding: “The Kitty I grew up with would never have allowed that to happen in her home.”

The brothers’ lawyer filed a writ of habeas corpus more than a year ago presenting the new evidence of abuse and arguing the brothers had acted in self-defense, along with a request for re-sentencing arguing the brothers have been rehabilitated and should be released.

Los Angeles District Attorney George Gascon has set a hearing for Nov. 29 to consider the new evidence.

In the meantime, Ryan Murphy’s hit Netflix show Monsters: The Lyle and Erik Menendez Story has generated frenzied interest in the case, though the brothers have slammed their depiction in the series.