Michael Peterson made a frantic call to the police - claiming he had found wife Kathleen unoncscious at the bottom of a staircase.
The American author, 78, said his partner had slipped and fallen to her death in their North Carolina home, but the blood on the stairs and wounds on her head led police to believe this may not have been an accident.
Peterson, who was the last person to see his wife alive, pleaded guilty to killing wife Kathleen by involuntary manslaughter as part of an 'Alford plea' but has always insisted he did not kill her.
Kathleen's death and subsequent trial has been described as the the most captivating real life true crime story you've never heard of - and now Colin Firth is playing Peterson in new Sky Atlantic drama, The Staircase.
A postmortem showed that Kathlen had died from blood loss and had several lacerations on her head which we consistent with the use of a rigid murder weapon.
The medical autopsy found that the 48-year-old had sustained a litany of severe injuries, including a fracture of the thyroid neck cartilage and multiple lacerations to the top and back of her head.
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A foresnic expert hired by Peterson's defence testified that the blood-spatter evidence was consistent with an accidental fall down the stairs.
But police investigators concluded that the injuries were inconsistent with such an accident and Peterson became the prime suspect because he was the only person at home at the time.
The trial drew huge attention when it was revealed that Peterson had been having affairs with male sex workers and could pocket $1.5million from a policy on Kathleen’s life.
Peterson claimed Kathleen knew about and accepted his extra-marital affairs, but the prosecution argued that said she had only recently found out and confronted him on the very night of her death.
Assistant District Attorney Freda Black said Kathleen: "Would have been infuriated by learning that her husband, who she truly loved, was bisexual and having an extramarital relationship. Not with another woman, but a man, which would have been humiliating and embarrassing to her."
The entire Peterson family was initially united, with Kathleen's daughter, Caitlin, and sister, Candace Zamperini, proclaiming his innoncense and supporting him alongisde his kids.
However, Candace changed her mind after discovering Peterson had been sleeping with men and Caitlin also reconsidered after reading her mother's autopsy report and broke off from the rest of the family.
It also emerged that a female friend of Peterson’s, Elizabeth Ratliff, had been found at the foot of her staircase with head injuries 16 years earlier when they all lived in Germany.
The body of Ratliff, whose daughters Margaret and Martha were adopted by Peterson, was exhumed during Peterson's trial and a new autopsy determined cause of death was homicide.
He was never charged with Ratliff's death, but the prosecution argued that it could have given him the inspiration to try and kill his wife in a similar way.
In 2005, Peterson was convicted of beating his wife to death and sentenced to life in prison with no possibility of parole.
Following Michael's conviction for murder, his lawyers launched an appeal and even had an alternative theory of who killed Kathleen - an owl.
The Owl Theory, which was first mooted by the Peterson's next-door neighbour and lawyer Larry Pollard, claims all the evidence points to Kathleen being attacked by a predatory bird.
Mr Pollard theorised that Kathleen was 'slammed' by an owl by the family's swimming pool, ripped out her own hair as she tried to get the bird off her head, then rushed into the house to escape and fell down the stairs.
Owls were known to live in the neighbourhood in Durham, and Mr Pollard said the wounds on her head look like they were created by the bird's talons, Kathleen's own hair was found in her hands and a microscopic feather was found on her body.
The evidence was so compelling that if Peterson had gone for a second trial it could have been seen as reasonable doubt, he and his lawyers did not want to risk another trial solely on the owl theory.
One of the key figures in the case was FBI analysts Duane Deaver, who testified against Peterson, but there were flaws in his evidence on the blood splatter.
He was fired from the Bureau for allegedly falsely reporting blood evidence in major trials and his testimony in the Peterson case was now seen as possibly inaccurate.
In December 2011, Peterson was released from the Durham County jail on $300,000 bail and placed under house arrest with a tracking anklet after a judge ruled Deaver had given "materially misleading" and "deliberately false" testimony.
Instead of a second trial, Peterson pleaded guilty to killing Kathleen by involuntary manslaughter as part of an 'Alford plea' in February 2017.
The Alford plea meant that Michael agreed the prosecution had enough evidence to coonvince a judge or jury he was guilty, but he was not admitting guilt.
Having already served eight years in prison, Peterson walked free from court in 2017, saying it was the "hardest thing I've ever done" in a conference just after his hearing.
Kathleen's family still saw it as some sort of justice, with sister Candace looking at Peterson when she said: "Alford, Schmalford. You are pleading guilty and you will be regarded as a convicted felon forever."
After getting out, Peterson lived in a 1,200-square-foot, two-bedroom condo in the same town, Durham, North Carolina.
Following his release from prison, Peterson has written two books that detail a behind-the-scenes account of his imprisonment, trial and his life after jail.
He has donated the proceeds from his book to charity after he was advised that he was not allowed to keep them.
He was also the subject of a Netflix documentary in 2019 which was full of shocking revelations about Peterson’s complicated life, one of the most extraordinary moments happened off-screen.
Sophie Brunet, editor of Netflix documentary The Staircase, began a relationship with Peterson.
Director De Lestrade confirmed the affair, saying: "Life really is full of surprises. They had a real story, which lasted until May 2017. But she never let her own feelings affect the editing."
In July 2020, the infamous five-story Cedar Street mansion where Kathleen was found dead was put up for sale, but it was reported Peterson had not owned the house since he sold it for cut price of $640,000 in 2004.
Peterson now lives a modest life, after he failed to secure Kathleen’s life insurance policy, and his step-daughter Caitlin obtained a $25million settlement via a wrongful death claim against him.
Now the story is being told in a new Sky Atlantic drama, which is being released today, starring Hollywood stars Colin Firth and Toni Collette as Michael and Kathleen Peterson.
Game of Thrones star Sophie Turner is playing adopted daughter Margaret Ratliff, while Patrick Schwarzenegger was cast as Michael's son Todd.
Firth has confirmed that he did not have any communication with Peterson because he did not want a personal connection to impact his performance.
"I felt the way the script was structured and just the whole approach of this was its own ecosystem, so to speak," he told Deadline in February.
"These are created characters but we all know what the source is. We all know that these characters have names of living people, but it’s very carefully calibrated to tell the story in a certain way."
"I felt that I wanted to keep my inspiration, my motivation, and the sense of the source material, as much as possible contained within the script and the way it was written."
The eight-part series attempts to piece together exactly what happened to Kathleen and follows the twists and turns that were seen in the Netflix documentary.
“I felt that that could have been skewed in some way if I had personal connections, during the shooting of this, with Michael Peterson and other people concerned.
"If I’d had a personal response to the meeting, it might have prevented me from tuning into this world of varying possibilities that had been created."
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