Colin Firth as Michael Peterson
Known for his work in A Single Man, The King’s Speech, The English Patient and Pride & Prejudice, UK actor Colin Firth takes on the role of novelist Michael Peterson.
After the death of his wife in 2001, Michael was convicted of murder in 2003 despite pleading ‘not guilty’ and was sentenced to life in prison.
The charge was reduced to manslaughter 14 years later, and he was sentenced to time already served. Michael maintains his innocence to this day.
Toni Collette as Kathleen Peterson
Toni Collette, who was recently in the Netflix series Pieces of Her, plays Kathleen Peterson, an executive for a telecommunications firm who was married to Michael for four years.
The couple shared five kids: two biological sons, a biological daughter and two adopted daughters. They lived in Durham, North Carolina.
In 2001, Kathleen, who was 48 at the time, was found unconscious and in a pool of her own blood at the bottom of the stairs in her home. She died from her injuries.
Sophie Turner as Margaret Ratliff
Best known for playing Sansa Stark in the HBO fantasy series Game of Thrones, Sophie Turner has also featured in Barely Lethal, X-Men, Survive from 2020 and The Prince.
In The Staircase, she’ll be playing Michael’s adoptive daughter, Margaret Ratliff.
Margaret is one of two daughters to Elizabeth and George Ratliff, who were friends with Michael and his first wife when they lived in Germany.
When her parents died, Michael became the legal guardian of Margaret and her sister Martha.
Odessa Young as Martha Ratliff
Martha Ratliff, Margaret’s younger sister, was in college when the trial unfolded.
Her late biological mother, Elizabeth, became a major talking point in the trial, as she was also found dead at the bottom of a flight of stairs.
Michael claims the circumstances are completely coincidental.
Her role has been taken on by Odessa Young, who has previously starred in Assassination Nation, Shirley, Mothering Sunday and The Stand.
Michael Stuhlbarg as David Rudolf
You may recognise Michael Stuhlbarg for his work in Showtime’s Your Honor, Dopesick, The Looming Tower, Boardwalk Empire, and Steve Jobs.
In this new role, he stars as Michael’s lawyer of 15 years, David Rudolf, who headed up the defence team and their efforts in the trial.
Dane DeHaan as Clayton Peterson
Dane DeHaan is best known as Andrew Detmer in Chronicle, Harry Osborn in The Amazing Spider-Man 2 and Lockhart in A Cure for Wellness.
He plays Michael’s oldest son Clayton Peterson, who was born from his first marriage to Patricia Peterson. Clayton continues to stand by his father.
Patrick Schwarzenegger as Todd Peterson
Like his older brother, Todd Peterson supported his father throughout the documentary series. He is the second of Michael’s two sons from his marriage to Patricia.
Todd is played by Patrick Schwarzenegger, the son of Hollywood legend Arnold, whose screen credits include Scouts Guide to the Zombie Apocalypse, Moxie and Scream Queens.
Olivia DeJonge as Caitlin Atwater
Caitlin Atwater is Kathleen’s biological daughter from her first marriage to Fred Atwater.
While she initially supported her stepdad, Caitlin switched to the prosecution’s side in Michael’s case, after being shocked by the extent of her late mother’s injuries.
She’s played by Australian actress Olivia DeJonge, who starred in the Netflix series The Society and will soon appear in Baz Luhrmann’s Elvis as Priscilla Presley.
Parker Posey as Freda Black
Freda Black was the assistant district attorney and prosecutor in the case against Michael. She died in 2018.
Parker Posey, the actress behind this new role, has appeared in Scream 3, Blade: Trinity and Superman Returns and Netflix’s Lost in Space.
Vincent Vermignon as Jean-Xavier de Lestrade
Vincent Vermignon is best known for his work in Gangs of the Caribbean and Cut. He also appeared in an episode of the crime series Luther in 2019.
In The Staircase, he stars as the Oscar-winning documentarian behind the original docuseries, Jean-Xavier de Lestrade.
Juliette Binoche as Sophie Brunet
Also working on The Staircase documentary was editor Sophie Brunet, who became romantically involved with Michael during the course of filming.
The actress playing her is Juliette Binoche, who is known for The Unbearable Lightness of Being, The English Patient, Chocolat and Godzilla.
Rosemarie DeWitt plays Candace Hunt Zamperini
Candace Hunt Zamperini is the sister of Kathleen, and strongly believes that Michael is responsible for her death.
Rosemarie DeWitt, the actress behind her in this new series, has played the sister of Toni Collette once before in the comedy-drama series United States of Tara.
She’s also known for roles in Mad Men, Olive Kitteridge, Little Fires Everywhere, Rachel Getting Married and La La Land.
Tim Guinee as Bill Peterson
As Bill Peterson, Michael’s brother, we have Tom Guinee, who last appeared in Netflix’s Inventing Anna. He previously starred in Harriet and Warning: Parental Advisory.
His real-life counterpart, Bill, is a lawyer himself and continued to stay by his brother’s side throughout the trial and through jury deliberations.