From Harrison Ford to Colin Firth, The Staircase producers discuss the difficulty of casting Michael Peterson

At the center of The Staircase's story is Michael Peterson: a successful novelist, a politician, a seemingly good father, and a convicted murderer. Playing Peterson in any capacity would be a tall order, one only made more challenging by the success of the original Staircase docuseries, which chronicles his story. In other words, viewers know Michael Peterson. So how do you cast him?

That was the dilemma for co-showrunners Antonio Campos and Maggie Cohn when they set out to make a scripted version of the story everyone had come to know so well. And at first, they thought they'd found their answer in none other than Harrison Ford. "We originally had been to Harrison Ford," Campos says. "But we parted ways because he had to go do an Indiana Jones."

Just like that, they were back to square one. That's when Colin Firth's name came up. "He had never done a role like this, but we had gone through the Firth filmography and were just constantly struck by how dynamic he was," says Campos. "I remember watching Where the Truth Lies and there's this scene where Colin is defending his partner in the movie, played by Kevin Bacon. Kevin Bacon gets insulted and Colin goes and beats the crap out of this guy behind the club that they're playing at. And it's so vicious and it's so ferocious. It was this reminder of the danger that he could also play."

Alberto E. Rodriguez/Getty Images; Samir Hussein/WireImage Harrison Ford and Colin Firth

For Cohn, it was Firth's Oscar-nominated work in the 2009 film A Single Man that pointed to him as a great choice for Peterson. "He's playing a character that has a secret and he's going about his day and he's having these interactions with people, but he's harboring something within himself," Cohn says of Firth's Single Man character. "To have that tension and to be able to, at times, bring out the fact that it existed, but also as a viewer to forget that it existed, felt very important to the role of Michael Peterson. Because he was a father, he was a husband, he was a politician, he was also a man that had secrets, and we wanted to be able to choose which of those things was most prevalent when."

Then there's the question of Kathleen Peterson, the murder victim. It's a pivotal role for the show, but a particularly tricky one. "Kathleen is not someone that people know, and there's not footage of her and there's not audio of her," Campos says. "We needed to find an actor who could just immediately bring her a life and make her dynamic and complicated."

HBO Max Colin Firth and Toni Collette in 'The Staircase'

Cohn adds, "The fact is that Kathleen Peterson was kind of the missing part of the documentary, even though she was the most important part of the documentary. So I think while her character in many ways was 'less defined' than other characters, what she did have to play against was the perception of being a victim. And so it was important that we found an actress that had that power and that strength to overcome the idea that we know how this night ends for her. And so we needed an actor that made her feel alive up until that point. And I mean, Toni Colette is one of the most alive people on and off screen."

The first three episodes of The Staircase are streaming now on HBO Max.

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