(NewsNation) — Nearly two dozen family members of Erik and Lyle Menendez, the two brothers convicted of killing their parents in 1996, are holding a news conference Wednesday in Los Angeles in hopes it will move the needle in the brothers’ appeal of their conviction.

Los Angeles County District Attorney George Gascón announced earlier this month that he was reviewing new evidence in the case against the brothers.

New evidence allegedly includes a letter from Erik Menendez to a cousin before the killings. In it, Erik Menendez details some of the sexual abuse he survived at the hands of his father, Jose Menendez.

Plus, new allegations against Jose Menendez from a second, young boy claiming to have been raped by him at 14 have come into the spotlight.

Family stands by Menendez brothers

Family members have said the Menendez brothers should not have been charged with murder, but manslaughter — but that wasn’t an option.

The brothers’ extended family will advocate for the brothers’ release from prison during the news conference as prosecutors review new evidence to determine whether they should be serving life sentences for killing their parents.

Erik Menendez, now 53, and his 56-year-old brother, Lyle Menendez, are currently incarcerated in state prison without the possibility of parole after being convicted of killing their parents in their Beverly Hills mansion more than 35 years ago.

Lyle Menendez, who was then 21, and Erik Menendez, then 18, admitted they fatally shot their entertainment executive father, Jose Menendez, and their mother, Kitty Menendez, in 1989. However, they argued self-defense, saying they feared their parents were about to kill them to prevent the disclosure of the father’s long-term sexual molestation of Erik.

While testimony and evidence about the sexual abuse was allowed in the brothers’ first trial that ended in a hung jury, it was not allowed in the second trial that ended in guilty verdicts.

“I always believed that they were sexually molested,” Karen Vandermolen Copley told NewsNation’s Chris Cuomo earlier this month. “My sister Diane lived with them, and they have evidence that was not allowed. We have always supported the boys once we knew and understood the facts.”

The extended family’s attorney Bryan Freedman previously said they strongly support the brothers’ release. Comedian Rosie O’Donnell also plans to join the family Wednesday.

New evidence sparks case review

Earlier this month, Gascón said there is no question the brothers committed the 1989 murders, but his office will be reviewing new evidence and will make a decision on whether a resentencing is warranted in the notorious case that captured national attention.

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, attorney Mark Geragos previously said.

The case has gained new traction in recent weeks after Netflix began streaming the true-crime drama “Monsters: The Lyle and Erik Menendez Story.”

The new evidence includes a letter written by Erik Menendez that his attorneys say corroborates the allegations that he was sexually abused by his father. A hearing was scheduled for Nov. 29.

Prosecutors at the time contended there was no evidence of any molestation. They said the sons were after their parents’ multimillion-dollar estate.

In a recorded conversation in a Netflix documentary, Erik Menendez claimed the spending was to “cover up the horrible pain of not wanting to be alive.”

Jurors in 1996 rejected a death sentence in favor of life without parole.

NewsNation reached out to relatives and the brothers’ attorney for comment. However, they said they would not comment on the case until after Wednesday’s news conference.

The Associated Press contributed to this report.