The Menendez brothers were convicted in 1996. They have been serving life in prison without the possibility of parole. Their appeals have been repeatedly denied.
In a Thursday afternoon press conference, Gascón said there are many questions surrounding new evidence in support of sexual abuse claims the brothers made against their father, Jose Menendez.
He added that his office is evaluating all information but no decision on a possible resentencing for the brothers has been made.
He said he is "not leaning in any direction right now. I'm keeping an open mind." But he insisted, "the final decision will be mine."
One of the Menendez brothers' attorneys, Mark Geragos, commended Gascón for taking a "bold" step by reviewing the matter and agreeing to make the final call from his office.
Menendez brothers' attorney holds press conference after DA decides to review resentencing
"When they were convicted, California was in the throes of a prison expansion, a law and order expansion and frankly DA politics. And now we fast-forward 35 years later. We've got a much more robust and evolved understanding of abuse, yes abuse, can occur both with females and with males. I think it's time, their family thinks it's time, I believe that what you saw today with District Attorney Gascón was that he has taken, I think, a rather bold step in that he has said he's going to make the final decision," said Geragos. "It may not be a popular decision in prosecutorial circles, but I would think that in our culture we've come a long way in the last 10 years... I think we're at a point now where any reasonable person taking a look at this case believes they should be out."
The court papers filed by defense attorneys last year included a copy of the handwritten letter allegedly sent by Erik Menendez to his cousin, Andy Cano. Attorneys contend the letter was only recently discovered by Cano's mother. Cano, who died of a drug overdose in 2003, testified in the brothers' first trial that Erik Menendez had told him about the molestation by his father when Erik was 13 years old, according to the court documents.
In the letter, Erik Menendez writes in part, "I've been trying to avoid dad. It's still happening Andy, but it's worse for me now. I can't explain it. ... I never know when it's going to happen and it's driving me crazy. Every night I stay up thinking he might come in. I need to put it out of my mind."
Geragos said he believes the new evidence in the case is more than enough for a judge to "set aside the result" of the brothers' trial and overturn their conviction.
"They have now served 35 years," Geragos said. "In those 35 years that they have served in prison, they have been model prisoners. They have worked tirelessly in the face of literally no expectation that they would ever get out to reform not only themselves but the environment in which they find themselves."
Jose Menendez and his wife, Mary Louise, or "Kitty," were gunned down by their sons in their Beverly Hills mansion in 1989. Erik Menendez, now 53, and Lyle Menendez, now 56, never denied carrying out the killings, but contended they were repeatedly sexually assaulted by their father and feared for their lives.
Gascón reviewing possible resentencing in 1996 murder case of the Menendez brothers
Prosecutors, however, said the killings were financially motivated, pointing to lavish spending sprees by the brothers after the killings and arguing they were guilty of first-degree murder.
The brothers' first trial ended with jurors unable to reach verdicts, deadlocking between first-degree murder and lesser charges including manslaughter. The second trial, which began in October 1995 and lacked much of the testimony centered on allegations of sexual abuse by Jose Menendez, ended with both brothers being convicted of first-degree murder and conspiracy.
In response to Thursday's announcement by Gascón, the Beverly Hills Police Department issued the following statement:
"Erik and Lyle Menendez were sentenced to life in prison without the possibility of parole in July 1996 after being convicted of two counts of murder and conspiracy in the deaths of their parents, José and Kitty Menendez. As the investigating agency for the case, the BHPD presented the facts and evidence to the Los Angeles County District Attorney's Office at that time who proceeded with filing criminal charges.
"To date, BHPD has not been contacted by the Los Angeles County District Attorney's Office regarding these new developments.
"BHPD remains committed to transparency and working collaboratively with all agencies to pursue justice."
The case is drawing new interest after the release of the Netflix series based on the case.
City News Service Inc. contributed to this report.