Uncovering the Soul-Bearing Jailhouse Letter that Forced Lyle and Erik Menendez 'to Confess Everything' (Exclusive)

Lyle and Erik Menendez open up about their parents' slayings in the Netflix documentary 'The Menendez Brothers,' which streams beginning Oct. 7

<p>Ronald L. Soble / Los Angeles Times/ Getty</p> Erik and Lyle Menendez on the steps of their Beverly Hills home in Nov., 1989

Ronald L. Soble / Los Angeles Times/ Getty

Erik and Lyle Menendez on the steps of their Beverly Hills home in Nov., 1989

Erik Menendez was never supposed to keep the 17-page, soul-baring letter his older brother Lyle wrote to him in May 1990 when they were being held in county jail.

Lyle wrote the letter two months after he and his brother were arrested on suspicion of killing their parents, Jose and Kitty Menendez, on Aug. 20, 1989.

“Lyle couldn’t express what he did in that letter in person,” Erik, now 53, says in an exclusive clip from the upcoming Netflix documentary The Menendez Brothers, which is shown below. “It was easier for him to put it on paper.”

Lyle told Erik to destroy the letter after he read it, but Erik held onto it.

“It was a precious letter to me,” Erik says in the documentary. “It was one of those moments when Lyle was really expressing his own pain and I didn’t want to just throw it away because that didn’t happen often between us.”

Streaming on Oct. 7, The Menendez Brothers features recorded interviews from prison with Erik and Lyle, 56, who has not spoken publicly since he and his brother sat down with Barbara Walters in June 1996.

It also includes interviews with prosecutor Pamela Bozanich, juror Betty Oldfield and Kitty’s sister Joan Vander Molen.

Related: Menendez Brother Explains Why He Didn't Accuse Parents of Abuse When He Initially Confessed to Killings

Explaining why he believes Lyle never opened up to him before he sent the letter, Erik says in the clip, “He felt that telling the sick secrets of the family would be like killing my parents again and he did not want to do it.”

In a murder that shocked the nation and the world, in August 1989, Lyle, then 21, and Erik, 18, burst into the den of their family’s Beverly Hills, Calif., home and shot their parents at close range with 12-gauge shotguns as the victims sat on the couch and watched TV.

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During their first trial in 1993, which ended in mistrial, the brothers testified that they killed their parents after years of alleged sexual abuse by their Hollywood executive father, which they claim their mother ignored.

In 1996, they were sentenced to life in prison without parole.

The sensational case, which is the subject of season 2 of Ryan Murphy’s Netflix show Monsters: The Lyle and Erik Menendez Story, starring Javier Bardem and Chloë Sevigny.

For the documentary, the brothers spoke to director Alejandro Hartmann over a series of recorded calls from California’s Donovan Correctional Facility, where they are now incarcerated.

Related: Do the Menendez Brothers Have a Chance of Getting Out of Prison? Lawyer Says They're 'Cautiously Optimistic' (Exclusive)

In the clip, the brothers discuss what happened in 1990 — when jail officials, suspicious about a planned escape, searched their cells and found Lyle's letter.

“Ultimately it became clear, particularly after they found that jail letter, that there was no way around saying what happened because they had that note,” Lyle says in the clip. “They had a confession that we were responsible for our parents’ death.”

Erik says in the clip: “As a result of them finding this letter in the summer of 1990, we now had to confess to everyone.”

The Menendez Brothers airs on Netflix on Oct. 7.

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