Should I Marry a Murderer? - the love story that uncovered a killer

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."

It's precisely the complexity of Muirhead's personality that makes her such a compelling figure as, according to Allott, she "was articulate and intelligent, a promising young pathologist with eight years of medical training".

"She had her whole life on track and after meeting Sandy and hearing what he did, everything falls apart."

In the series, Muirhead talks candidly about how she turned to alcohol and drugs in a bid to cope with the situation she found herself in.

Allott and Beavis are clear their intentions are to present a balanced account of the events but want to ultimately highlight "what being on the periphery of crime but not involved can do to someone's life".

There is also a focus on the way the police conducted their relations with Muirhead after she came forward to report a crime.

Allott argues that the police "didn't know how to handle Caroline" and, without giving too much away, says that had she received "consideration and kindness from them she wouldn't have had to make some of the decisions she did."

Beavis agrees and adds that Muirhead's experience "echoes many experiences of people in the criminal justice system".

"The wheels of justice turn so slowly and that affects peoples lives and that's what we wanted to show."

Police Scotland and Victim Support Scotland declined to take part in the series.

Muirhead made multiple complaints against Police Scotland.

After a five-year investigation, the majority were not upheld and the police maintain they offered Muirhead appropriate support.

In a note about the show, Muirhead said she "trusted the system would stand by me and keep me safe when I was at my most vulnerable but that wasn't my experience.

"I hope by speaking out and sharing what happened to me, we can start an honest conversation about greater protection for victims and witnesses and why a far deeper understanding of mental health within the police and court system is so desperately needed.

"All too often the impact of trauma and abuse is overlooked or dismissed entirely and this means people like me are being left high and dry to pick up the pieces alone."

In July 2023, shortly before the brothers' trial was due to begin at the High Court in Glasgow, McKellar admitted the reduced charge of culpable homicide.

His brother had his not guilty plea to murder accepted, but the pair both admitted attempting to defeat the ends of justice by covering up the crime.

Sandy McKellar was sentenced to 12 years in jail, while his brother was jailed for five years and three months.

The case was also previously covered in BBC documentary series Murder Case: The Vanishing Cyclist.

Should I Marry a Murderer? is out now on Netflix.