The Staircase true story: Michael Peterson case explained

He pleaded 'not guilty' to the charge, insisting to this day that he wasn’t at all connected to Kathleen’s death, which began a legal battle spanning 16 years.

So what do we know about the murder case? Here’s a full breakdown of the true story that inspired HBO Max's drama series The Staircase, which is available on Sky Atlantic and NOW in the UK.

Is The Staircase based on a true story?

In the early hours of the morning on 9th December 2001, Michael Peterson found his wife, Kathleen, at the bottom of the stairs in their family home in North Carolina.

He called the emergency services saying that she was still alive and begging them to arrive with the greatest of urgency, but dialling back shortly after he reported that she had stopped breathing.

By the time paramedics arrived, Kathleen had passed on, with the nature of her injuries leading Durham police to treat the staircase as a crime scene.

Michael claimed that he had been in the garden by the pool at the time of Kathleen's fall, thus he could not have heard her struggle or had anything to do with the tragic incident.

Yet authorities questioned this story and, two months later, charged him with murder, an accusation to which he pleaded 'not guilty', beginning a lengthy battle in court.

The initial charge

The medical examiner who conducted the post-mortem on Kathleen was alarmed by several findings, most notable of which were the deep lacerations on her scalp which weren't consistent with a typical fall down the stairs.

In addition, it was found that her blood alcohol content at the time of death was low enough to pass a breathalyser test, which it was argued meant the death couldn't be chalked up entirely to a drunken stumble.

Meanwhile, doubt was also cast on Michael's initial 911 call, where he claimed that Kathleen was still breathing, as the blood at the scene was mostly dry when paramedics arrived – indicating the fall had taken place some time ago.

The prosecution alleged that the spatter pattern on the stairs suggested Kathleen had been struck by something, although crucially they were never able to find a supposed murder weapon.

Their initial theory, that Michael had used a fireplace tool called a blow poke, was debunked when the object was found in the garage undamaged and with no trace of blood on it.

Still, the prosecution case rested heavily on the aforementioned lacerations, with the medical examiner ruling the cause of death in this case to be homicide.

Another staircase death

Further complicating matters was the revelation that, during a period living in Germany many years earlier, one of Peterson's close friends had also been discovered dead at the bottom of her own staircase.

At the time, it had been thought that Elizabeth Ratliff – whose two daughters Michael became legal guardian of – had suffered a stroke on the stairs, but when her body was exhumed following Kathleen's death, the examiner ruled it another homicide.

This became another key talking point in the courtroom, with NBC describing discussion of the Ratliff case as a "mini-trial within a trial", although Michael's defence argued it was nothing more than a tragic coincidence.

While details relating to Elizabeth's death were somewhat hazy due to its historic nature and the minimal records filed at the time, the prosecution were prepared to speculate on a potential motive in the case of Kathleen.

Michael's sexuality

In the wake of Kathleen's death, authorities examined Michael's computer and found 2000 pornographic images of men on the hard drive, in addition to correspondence with a male prostitute with whom he discussed meeting.

According to sex worker Brad, the hook-up never went ahead, but the conversation alone was enough for the prosecution to argue that Michael and Kathleen's marriage may not have been as content as it outwardly appeared.

The defence hit back against these claims, arguing that Kathleen was fully aware of her husband's bisexuality, with his brother Bill stating it had not been something he'd been especially private about since their teenage years.

Indeed, that the household phone bill, which was in Kathleen's name, showed calls to Brad's number suggested this was no secret, while the male prostitute himself spoke of the high praise Michael gave his wife in their interactions.

The defence case

In addition to emphasising the strength of Michael and Kathleen's relationship (and therefore lack of motive), defence lawyer David Rudolf brought in his own expert to give his analysis of the staircase scene.

Neuropathologist Dr Jan Leestma argued that Kathleen's injuries could well have been sustained in an accidental fall, noting that the lack of skull and bone fractures were not consistent with a beating.

Meanwhile, medical examiner Dr Henry Lee testified that the unusual spatter could have been caused by Kathleen coughing up blood, rather than being struck as the prosecution had argued.

Rudolf also called the police work into question, alleging that the crime scene had not been properly cordoned off when authorities arrived.

Indeed, when Michael's son Todd arrived that fateful night to console his father, he was allowed to enter the kitchen for a soda, despite carrying blood on him that had been transferred from his father.

Also helping his defence was the fact that most of Michael's family stood by him throughout the trial – including sons Clayton and Todd, brother Bill, and Ratliff's daughters Margaret and Martha – citing the love between himself and Kathleen.

Kathleen's biological daughter Caitlin Atwater and sister Candace Hunt Zamperini sided with the prosecution.

Ultimately, Peterson was found guilty in the initial trial, but that was far from the end of the story.

The Alford plea

A retrial was eventually ordered in 2011, after a blood spatter analyst for the prosecution was found to have given misleading testimony in the initial hearing.

Some six years later, Peterson and Rudolf submitted an "Alford plea" of voluntary manslaughter, which allows the defendant to continue asserting their innocence, while conceding that there is enough evidence against them for a conviction.

It led to a reduced sentence of 86 months in prison, which had already been served by Peterson's jail time since 2003.

The owl theory

As Peterson maintains his innocence to this very day, it is still unclear what exactly happened to Kathleen Peterson that fateful night in December 2001.

One theory that emerged in 2009 and has captured the imagination of true crime fans is that she was attacked by a barred owl – a common species in Durham, North Carolina – with evidence at the scene backing this idea.

The lacerations on her scalp could have been caused by sharp owl talons, which would explain the lack of bone fractures, although experts are divided on whether the bird could have caused such deep wounds.

Additionally, the post-mortem found pine needles stuck to one of Kathleen's hands and three small feathers in the other, caught between strands of her own hair.

Attorney Lawrence Pollard described the evidence as "compelling", but it did not lead to anything.

The Staircase airs Thursdays on Sky Atlantic – sign up for Sky TV here. You can also stream episodes on NOW. Check out more of our Drama coverage or visit our TV Guide to see what's on tonight.

The latest issue of Radio Times magazine is on sale now – subscribe now and get the next 12 issues for only £1. For more from the biggest stars in TV, listen to the Radio Times podcast with Jane Garvey.