Sophie Turner Cast Alongside Colin Firth and Toni Collette In Upcoming Series "The Staircase"

Actor Sophie Turner has joined the all-star cast for the upcoming series “The Staircase," a dramatizing of the Michael Peterson murder case.

HBO Max announced that the series is in the works back in April. Oscar-winning actor Colin Firth, known for his roles in “The King’s Speech” and “Bridget Jones’ Diary,” was cast as Peterson. Turner and Firth will star alongside Toni Collette, Parker Posey, Juliette Binoche, and Rosemarie DeWitt, Variety reports. Turner will be portraying  one of Peterson’s adopted daughters, Deadline reports. Collette has been cast to play Peterson’s wife, DeWitt will play his sister-in-law, and Posey to portray the prosecutor in the case.

Peterson was convicted in 2003 for the murder of his wife, Kathleen Peterson, who was found dead at the bottom of a staircase in their North Carolina home in 2001 with lacerations on her head. Her death spawned many theories, including one that an owl had killed her.

Alarmingly, Kathleen Peterson was one of two women to whom her husband was connected and found dead at the bottom of a flight of stairs.

The first woman, 43-year-old Elizabeth Ann McKee Ratliff, was a friend of Peterson and his first wife, Patricia, when they lived in Germany. Ratliff was found dead in her home after having dinner with the Petersons the previous night. Peterson was the last person known to see her alive, but the initial autopsy determined she died of an accidental fall and related brain hemorrhage.

While Peterson, a novelist, spent nearly a decade behind bars for his wife's death, he was granted a new trial in 2011 after a judge determined that a key prosecution witness, Duane Deaver, provided unreliable testimony during his trial. Deaver had testified that bloodstain analysis from the scene indicated that Kathleen Peterson's injuries were sustained during a fatal beating — not from an accidental fall. Deaver was fired from the North Carolina State Bureau of Investigation in 2011 after allegedly providing false testimony at a number of trials.

Then in 2017, just months before the scheduled retrial, Peterson submitted an Alford plea to the reduced charge of manslaughter. The plea deal acknowledged there was enough evidence to convict him at trial, while still allowing him to maintain his innocence. He was sentenced to time served and the court declared that he would never face another day in court, or jail, for his wife's death.

The entire case was examined in Netflix’s 2018 docuseries, also named “The Staircase.” 

Maggie Cohn, who produced “The Assassination of Gianni Versace: American Crime Story” will serve as co-showrunner for the upcoming eight-episode series.

"This has been a project I have been working on in one way or another since 2008," the project’s executive director Antonio Campos wrote in a statement, obtained by Entertainment Weekly in April. "It's been a long and winding road, but well worth the wait to be able to find partners like HBO Max, Annapurna, co-showrunner Maggie Cohn, and the incredible Colin Firth to dramatize such a complex true-life story."