LOS ANGELES – Gus Halper is glad he didn’t know anything about the Menendez brothers until he was hired to play Erik in the limited series “Law & Order True Crime: The Menendez Murders.”

“I got to approach it with a new set of eyes,” he says. Audiences could, too.

 Gus Halper plays Erik Menendez in "Law & Order True Crime: The Menendez Murders." NBC

Although the trial attracted international attention, it didn’t give viewers a look at what happened before the two killed their parents. Erik, Halper says, was abused sexually and psychologically by his father and felt threatened if he ever said anything about his situation. He was also told what to do by his brother, Lyle, and “took after his mom a lot more emotionally and personality-wise.”

Because the two grew up in a wealthy household, there were assumptions when the case hit the news. “People want to be entertained but they don’t necessarily want to challenge their preconceived notions of something,” Halper says. “There was this kind of raw meat feeding frenzy: ‘What’s next? What’s the next salacious fact?’”

As the trial wore on, many family secrets spilled out. In the series, “you get to see everything that happened during the trial,” Halper says. “This is a really searing look at the whole thing. It covers almost everything that I’ve researched.”

Erik, he says, cracked and admitted guilt to his therapist. “He couldn’t deal with this, what he did and a lot of the psychological effects of sexual abuse.”

Miles Gaston Villanueva, left, and Gus Halper play the Menendez brothers in a new limited series. NBC

Because he idealized his father and couldn’t understand why he would hurt his son, Erik “turned it on himself.”

While Halper and Miles Gaston Villanueva (who plays Lyle) didn’t interview the two brothers, who are now in prison, they had plenty of questions.

Among Halper’s: “What would he most want to do to help victims of sexual abuse?” “I think the answer would be revealing about his own experience.”

A New York-based actor, Halper says he also grew up in a privileged home but couldn’t imagine what would lead someone to kill his parents. “A lot of research shows it has to do with the psychological effects of sexual abuse.”

During the filming, Halper and Villanueva looked for ways to deal with the dark subject matter.

From left, Gus Halper as Eric Menendez, Miles Gaston Villanueva as Lyle Menendez "Law & Order True Crime." NBC

The two often went out to dinner after shooting, respected each other’s space and talked about the case. “It’s not the easiest place to live for a long time,” Halper says.

Before “Law & Order,” Halper was in “Goat,” a film about fraternity hazing gone awry. “It’s a different type of abuse but it was easier (to perform) because that character was in denial about it. I didn’t have to deal with any of it. Erik is different – the level of abuse he endured is surprising.”

While most actors would like to be on a long-running series, Halper says something like “Law & Order” offers a definite ending.

“It’s finite: Here’s the beginning. Here’s the ending. This is our job. Once it’s done, you can let it go.”

“Law & Order True Crime: The Menendez Murders" airs at 9 p.m. Tuesdays on NBC.