It’s been more than 27 years since Erik and Lyle Menendez brutally murdered their parents in August 1989. The infamous double homicide of Kitty and Jose Menendez is being revisited in NBC’s Law & Order True Crime: The Menendez Murders — and true crime enthusiasts are still wondering why Erik and Lyle viscously killed their mom and dad.

Over the years, the brothers — who are currently serving life sentences in two separate California prisons — have opened up in interviews about shooting down Kitty and Jose in their family’s Beverly Hills mansion. This past January, Lyle, 49, told ABC News how he has learned to live with the crime. “I am the kid that did kill his parents, and no river of tears has changed that and no amount of regret has changed it," he said. "I accept that. You are often defined by a few moments of your life, but that’s not who you are in your life, you know. Your life is your totality of it.”

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Lyle’s mugshot.

Erik, 46, is more press shy, but during a 2005 interview with People, he suggested that a rough upbringing served as the catalyst for his decision to take his parents’ lives. “I killed the two people I loved the most. I loved my dad. Listen, how much anger can you have towards someone after killing them? I loved my parents. And that is my real prison. I look forward to dying,” he explained. “Oh, people say that I had everything, that I was rich and lived in Beverly Hills. But if you had photos of the events of my childhood, they would be crime photos. I was dying long before the night I killed my parents.”

Earlier this year, ABC debuted Truth And Lies: The Menendez Brothers, a two-part special about Erik and Lyle’s gruesome crime. In the special, photographer Philip Kearney — known for taking shirtless modeling photos of Erik — claimed that his former friend fantasized about killing his parents and even wrote a screenplay about it. According to Philip, the script was “about the boy who kills his parents to collect the insurance.”

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Erik’s mugshot.

“As time went by, Erik took that screenplay and reworded the first four or five pages to exactly what happened in the crime,” Philip continued, adding that he felt a “chilling realization” when he saw the Menendez murders play out on the news.

Prosecutors believed that the Menendez brothers’ main motivation was greed. In ABC’s special, Kitty and Jose’s friend Karen Ferrell echoed this notion, saying that Lyle and Erik were scared of being written out of their parents’ will. At the time, Jose — a prominent Hollywood producer — and his wife were worth an estimated $14 million. Karen recalled a moment when Kitty was at the family computer updating her will and speaking openly about removing her boys’ names. "She said, 'I don’t care. They know I’m not gonna give them any money,’” Karen remembered.

However, Lyle and Erik — who were 21 and 18 at the time, respectively — eventually said that they killed their mother and father because they were fearful of their own lives, and claimed that both their parents had emotionally abused and molested the siblings from a very young age. “My own childhood prepared me surprisingly well for the chaos of prison life. You feel that loss of freedom deeply,” Lyle has said. “It’s shocking to think about that that happened. It’s still jarring. Like, it seems so far removed from who I am and who I was. It could have so easily not have happened.”

Law & Order True Crime: The Menendez Murders airs Tuesdays at 10 p.m. EST on NBC.