"I had no idea the extent of the abuse they suffered at the hands of my brother-in-law. None of us did," said Joan Andersen VanderMolen, Kitty Menendez's sister. "We know that abuse has long effects, and victims of trauma sometimes act in ways that are very difficult to understand."
"The whole world was not ready to hear that boys could be raped," she said, adding "today we know better."
The Menendez brothers' case: monsters or victims?
The news conference in downtown Los Angeles was the largest gathering of the extended family since the brothers' 1996 sentencing. The public call for their release comes less than two weeks after the Los Angeles County district attorney announced his office would be reviewing new evidence to determine whether the brothers should be serving life sentences.
The brothers' defense attorney Mark Geragos and their family previously told ABC News that their biggest wish is for the two to be released from prison and be home in time to celebrate their aunt's 93rd birthday this Thanksgiving.
The new evidence presented in a petition includes a letter written by Erik Menendez that his attorneys say corroborates the allegations that he was sexually abused by his father.
The brothers have said they killed their parents out of self-defense after enduring a lifetime of physical, emotional and sexual abuse from them. Their attorneys argue that because of society's changing views on sexual abuse, that the brothers may not have been convicted of first-degree murder and sentenced to life without parole if the case was heard today.
"Twenty-four all signed a letter saying 'Hey, we want them out as well.' That is basically unheard of. In my 40 years of practice, I never had... a kind of a failings of victims who have all signed on to say 'Enough is enough, we want them out'," Geragos said.
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The brothers' attorneys said the family believed from the beginning they should have been charged with manslaughter rather than murder. Manslaughter was not an option for the jury during the second trial that ultimately led to the brothers' murder conviction, Geragos said.
Lyle Menendez, who was then 21, and Erik Menendez, then 18, admitted they fatally shot-gunned their entertainment executive father Jose Menendez and their mother, Kitty Menendez, in 1989 but said they feared their parents were about to kill them to prevent the disclosure of the father's long-term sexual molestation of Erik.
Prosecutors at the time contended there was no evidence of any molestation. They said the sons were after their parents' multimillion-dollar estate.
Jurors rejected a death sentence in favor of life without parole.
"They tried to protect themselves the only way they knew how," said Brian A. Andersen Jr., nephew of Kitty Menendez. "Instead of being seen as victims, they were vilified."
"They are no longer a threat to society," he continued.
Others in the family echoed similar sentiments. "If Lyle and Erik's case were heard today, with the understanding we now have about abuse and PTSD, there is no doubt in my mind that their sentencing would have been very different," said Anamaria Baralt, a niece of Jose Menendez.
On Wednesday, Gascón's office said prosecutors met with the family members after the news conference and the case's evidence and sentencing are under review.
"Our office has developed a more modern understanding of sexual violence since the Menendez brothers first faced prosecution," the DA's office said in a statement. "Today, our office acknowledges that sexual violence is a pervasive issue affecting countless individuals - of all gender identities - and we are committed to supporting all victims as they navigate the profound impacts of such trauma."
The case has gained new attention after Netflix began streaming the true-crime drama "Monsters: The Lyle and Erik Menendez Story. "
Gascón said he believes that the topic of sexual assault would have been treated with more sensitivity if the case had happened today.
"We have not decided on an outcome. We are reviewing information," Gascón said earlier this month.
He said his office did not know the "validity" of what was presented at the trial.
Gascón, who is seeking reelection, noted that more than 300 people have been resentenced during his term, and only four have gone on to commit a crime again.
Lyle Menendez recently earned a sociology degree from the University of California, Irvine, through a prison program. Geragos said they have been model prisoners despite believing they would never be released.
"I think it's time," Geragos said. "The family thinks it's time."
Reality TV star and celebrity personality Kim Kardashian, who has advocated for criminal justice reform, also weighed in, writing in a personal essay shared with NBC News that the outsized media attention on the first trial that was nationally televised denied them justice.
She noted with "their suffering and stories of abuse ridiculed in skits on 'Saturday Night Live'" that they were painted as "two arrogant, rich kids from Beverly Hills who killed their parents out of greed. There was no room for empathy, let alone sympathy."
"Erik and Lyle had no chance of a fair trial against this backdrop," Kardashian wrote.
The Associated Press and ABC News contributed to this report.