How Sam Worthington and Wyatt Russell Approached Under the Banner of Heaven Portrayals

It goes without saying that playing a convicted murderer isn't an easy feat to pull off.

So Under the Banner of Heaven stars Sam Worthington and Wyatt Russell knew they had their work cut out for them when they agreed to play Ron and Dan Lafferty, two brothers who killed their sister-in-law, Brenda Lafferty, 24, and her 15-month-old daughter, Erica, in 1984. (The brothers, who came from a devout and prominent Mormon family in Utah, claimed that God ordered them to commit the crimes.)

Worthington told E! News that he couldn't begin to understand what would motivate someone to do such a thing. And then he realized through working with writer Dustin Lance Black that "you can't play delusional, but you can play someone that is passionately pursuing something."

In the series, the Laffertys appear to be a normal, loving family, begging the question: "How could this event happen in such a pious and devoted community? In such a loving family?" Worthington said. "So the more I strengthened and leaned into a man that would do anything for the love of his kids and for the love of his wife, it gave me a touchstone of how to play certain scenes."

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Worthington said that reading the scripts and tracing the events that led up to Brenda's murder further allowed him to understand the "devoted family man" he was playing. "Little things like a competition between the brothers or a longing for touch or taking away the rights and privileges—and in Ron's case, his job, his religion, his kids," he explained. "Suddenly, we understand the building blocks to why they go into this descent."

The same goes for Russell, who felt that the brothers acted out of the desire to gain their parent's approval, a characteristic that he thinks isn't "exclusive to Mormon culture."

"It was important for the story that you really understood that they all want to be loved by their father," Russell explained, "and he has different versions of how he shows that love and manipulates his own children, which is the scary part."

Of course, the actors understand that Under of the Banner of Heaven will elicit strong reactions from the Mormon community, since the religion's origins are paralleled with the murders. However, Russell said, "I'm not here to tell anybody how to feel or think, or how they should feel about their own lives inside of their own religion. I'm just here to tell a story, and they can do what they want with it."

Under the Banner of Heaven airs Thursdays on FX on Hulu.

Don't miss the debut of E! News' digital series, While You Were Streaming, on Friday, May 27, at 9 a.m. PT on Twitter @enews! We'll be recapping the biggest moments from the premiere of Disney+'s new series Obi-Wan Kenobi.