For Allott, it was that emotional and moral tension that made the story impossible to ignore.
“The dilemma is impossible not to imagine in your own relationship, it makes you think about what would you do in her position as it’s a terrifying, nightmare scenario.”
Muirhead reported the crime to the police but what she did next is what makes the story so extraordinary and, arguably, explains why the series exists at all.
Rather than walking away, Muirhead continued the relationship, all while secretly going to the police and cooperating with their investigation, without McKellar knowing she was the one who had reported him.
It would be almost three years after McKellar first confessed to Muirhead that he would be handed a prison sentence.
During that time, Muirhead recorded secret confessions on her phone and went back to the Auch Estate with McKellar where she secretly dropped a Red Bull can as a marker for the spot, before later calling police to tell them where to search for the body on the remote estate.
While some may question such decisions, Allott says Muirhead did the right thing by reporting the crime to the police.
The brothers were arrested in December 2020 and released on bail – they were only charged in December 2021.
“She expected the brothers to be remanded in custody, face trial and be in prison forever and be out of her life but they were thrust back into her life,” Allott explains.
He says that she had to navigate this uncertain period alone as she was “left exposed to them for almost a year and that’s where the decisions come into it.”