It's not about what they did, but why they did it.

That's essentially the tagline of Law & Order True Crime: The Menendez Murders — and the show will aim to show just that. The cornerstone of the argument for why Erik and Lyle Menendez brutally murdered their parents is abuse — and a lot more information about what exactly went on in their childhood home has come to light since the trial in the '90s.

"I learned a tremendous amount about these young men that I didn't know and the abuse from their parents," Edie Falco, who will play the Menendez's attorney Leslie Abramson in the Dick Wolf series, told TV Guide. "Abuse is just a word but a lot of information is available now about what that specifically meant in their case, the kind of family they grew up in. The kind of illness that must of been present for parents to behave that way toward their children is beyond my scope of knowledge."

Abuse cases are typically difficult to prove, but the research team and cast were able to get their hands on a lot of corroborating evidence to back up the brothers' claims.

"It's not just an easy answer," Miles Gaston Villanueva said to us. "There are reasons why they did what they did and we have an opportunity to share that with everyone."

Law & Order True Crime: The Menendez Murders premieres Tuesday, Sept. 26 at 10/9c on NBC.