[This article contains spoilers for the finale of "Murdaugh: Death in the Family."]

LOS ANGELES — Jason Clarke insists he's not a method actor, but to take on the role of Alex Murdaugh, he became so immersed in the world of the disgraced lawyer and convicted killer that he often dreamed about him.

The role of Alex in Hulu's "Murdaugh: Death in the Family" demanded a lot of Clarke — mastery of a South Carolinian accent, adoption of Southern charm, significant weight gain and the emotional stamina to tap into the psyche of a man who killed his wife and child.

Clarke reveled in the challenge. "Like a Sherlock Holmes sleuth," he said, "you've got to crack it."

That meant Clarke spent hours thinking about Alex's perspective on the crumbling of his family's legal dynasty, the investigations into his finances, the murders of his wife Maggie and son Paul, and his eventual trial.

"It just started to sit inside me," he said on a Zoom call from New York in October. As Clarke was developing his version of Alex, his extensive work led him "to dream about it, to think about it, to justify him, to listen to that court case, to argue his way out of it, to find the mistakes or the injustices that he suffered in the trial that I thought I heard or saw."

His dreams primarily revolved around the trial — arguments between Alex and his legal team, evidence that was contested and Alex's fixation on justification for his actions.

"Murdaugh: Death in the Family," which released its finale Wednesday, dramatizes the yearslong mysteries surrounding the family, including a deadly boat crash, the sudden death of the family's housekeeper, serious financial crimes and the murders of Maggie and Paul. Co-starring with Clarke are Patricia Arquette as Maggie, Johnny Berchtold as Paul and Will Harrison as Alex's eldest son, Buster.

Beyond the emotional character work Clarke did, which included studying the recordings of the trial, reading books on psychology, and working with dialect coach Tim Monich, Clarke underwent a physical transformation to become Alex. He gained about 40 pounds, wore a wig and dyed his eyebrows since he did not want to rely on prosthetics. The physicality of the character helped everything click into place.

"I'm not a Method actor, but you're allowing it to creep into you, you know what I mean? You're allowing yourself to creep into it," he said. "All of a sudden, you become the reflection you see, with the lenses on, with the hair, with the makeup, with the weight, the suit, with the clothes, that all of a sudden, hang on. I am what I am. And there's nowhere I won't or can't go."

Clarke is no stranger to playing characters based on real-life people — he portrayed Sen. Ted Kennedy in the 2017 film "Chappaquiddick," L.A. Lakers general manager Jerry West in the HBO series "Winning Time: The Rise of the Lakers Dynasty," mountaineer Rob Hall in 2015's "Everest" and attorney Roger Robb in 2023's "Oppenheimer" to name a few.

Series co-creator and showrunner Michael D. Fuller said Clarke's performance in "Oppenheimer" showed him Clarke could pull off the challenging role. Although the characters are very different, Fuller said he saw the "physicality, the confidence, the masculinity" required to play Alex in that performance. And Fuller's hunch proved correct — at least in the eyes of Mandy Matney, the journalist whose podcast provided source material for the series and who was an executive producer on it. According to co-creator Erin Lee Carr, Matney "would get a chill in her body because she felt like she was looking at and talking to Alex Murdaugh."

"He's just one of our best living actors," Fuller said. "There's always something human about him, there's always something confident about him, and then there can be something scary about him. That's why I think he was singular for this part."

The series' finale was the ultimate test of Clarke's skills. It follows the theatrics of Alex's trial and depicts the full sequence where Maggie and Paul are murdered. Their murders were first depicted in an earlier episode, but the audience doesn't see the killer in that instance. However, in the finale, Alex is depicted as the perpetrator.

In the courtroom scenes, much of Clarke's dialogue is lifted directly from court transcripts. "Oh, what a tangled web we weave," Alex says in response to the prosecutor questioning why he lied about his whereabouts on the night of the murders.

That line, Fuller said, is "on the nose, but it's also spot-on." Striking a balance between what statements Alex and others made and taking creative license was all about "finding those little breadcrumbs that give it that sense of reality and authenticity."

Clarke said he poured over recordings of the trial, listening to them first before he watched the videos, partly as a way to nail down the specificities of Alex's accent and cadence. Re-creating moments shown or discussed in documentaries, podcasts and in the frenzy of news coverage about the case felt like an important piece of the dramatization for Clarke. If he looked like Alex and talked like Alex and some of the most memorable moments were word-perfect, "then the rest of what we build will have much more authenticity and believability," Clarke said.

The moments that haven't been documented — what family life looked like inside the Murdaugh home, what Maggie and Alex's marriage was like behind closed doors and what exactly happened on the night of the murders — are where Clarke, the cast and the writers needed to rely on the trust they had built with the audience.

A methodical, yet simplistic approach to filming the murder sequence in the finale was important to both Clarke and the co-creators. Fuller said on the two nights they spent filming that scene, the cast and crew took a moment to acknowledge the real-life victims and the event they were about to dramatize and ensure they were "treating it with the reverence and sensitivity it requires."

As Alex is shown carrying out the murders, he acts quickly and surely, and his face is nearly emotionless.

"You don't want to do things that don't need to be done because you undermine the rest of it," Clarke said. "There's a coldness to what happened. It was the act itself."

Clarke said shooting that scene was "not something you want to do too many times." What seems to have struck him the hardest, especially as a father of two sons, was that Murdaugh didn't "have to be filled with hate or anger" to kill his family members. In the series, Paul gets a glimpse of Alex just before he deals the final blow, which is a moment that Clarke wanted to emphasize. "That's the full horror," he said.

The actor referenced his work on the 2019 horror movie "Pet Sematary," in which he plays a father whose daughter is killed (and then resurrected with a new, disturbing demeanor), saying those types of roles have become increasingly challenging to perform. Clarke said, "I don't know how much more of that I can do."

The final moments of the series show Alex alone in his cell, catching a glimpse of his reflection after joking with (and swindling) a fellow inmate. When he sees himself, his reflection appears in the blue raincoat he wore when he killed Maggie and Paul. It's a reference to "The Man in the Glass" poem — which the real-life Murdaughs had framed in their home — about personal integrity and accountability.

"The only person he cannot lie to is himself when he's alone," Carr said.

That moment was initially conceived as something much more emotional, Fuller said, but Clarke pushed back on that, favoring a more ambiguous look on his face. He wanted the audience to interpret that moment on their own, and Fuller agreed.

"We're not going to hang a lantern on exactly what he's feeling here," Fuller said. "He's still alive, he's still in that prison cell, both in real life and in our story."

After filming wrapped, Clarke took a beach vacation with his sons and his wife (their trip was much more relaxing than Murdaugh's escape to the Caribbean depicted in the series). He still had red eyebrows, he was still heavier than usual from the shoot and he was "still a bit sensitive," he said. But eventually, he dropped the weight, his eyebrows returned to their natural shade and he was able to tap back into the fun he had on set when he needed to rerecord dialogue and put the finishing touches on the series. He was able to appreciate playing to Alex's swagger and charm and embracing the collaborative spirit of the set.

"As much as it hurt, it was enjoyable, and I'd be dishonest to say otherwise," he said. "I enjoyed disappearing."

There's still some parts of Alex he can't quite seem to shake yet, though, as evidenced by how easily he's able to swap his Australian accent for a distinct Lowcountry drawl over the course of the conversation.

"I still love that accent. "I love 'bo,'" he said of the South Carolinian equivalent of "mate." "I still find myself calling people bo, they just don't get it. Australians don't get it."

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