The Sixth Commandment falls victim to the inherent problem with true crime

The appetite for Dahmer was as voracious as it ever had been. People can't get enough of his depravity, a type of horror that's so utterly unfathomable, almost mind-bending in its abhorrence, viewers should run in the opposite direction. But instead, they lean in, eager to hoover up every last crumb. And even then, the desire for more lingers.

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Speaking about Dahmer and The Sixth Commandment in the same breath feels vastly unfair – the critical consensus about the former is that it's exploitative and much of it unnecessary, whereas the latter isn't that. But there's a shared by-product that is intrinsic to the genre as a whole.

The BBC drama tells the story of Peter Farquhar and Ann Moore-Martin, two elderly individuals who were preyed upon by PhD student and Baptist minister's son Ben Field for financial gain. He manipulated both into believing that they were in loving relationships with him all while subjecting them to an extensive gaslighting campaign, which included writing messages from God on Moore-Martin's mirrors asking for money (both of them were deeply committed to their religious faith).

Field was also slowly poisoning Farquhar, who he eventually suffocated to death, and while there was no evidence to suggest he had drugged Moore-Martin, she alleged that he had given her some white powder.

It's a particularly striking tale, not just because of the extent of Field's cruelty towards Farquhar and Moore-Martin – both had family and friends to speak of, but lacked the intimate connection of a romantic partner, which Field seized upon. For Farquhar, who was gay, that stemmed from him being unable to reconcile his sexuality with his faith. But it's also arresting because the tragedy unfolded in the sleepy village of Maids Moreton in Buckinghamshire, right under the noses of family, friends and neighbours.

From the outside looking in, it was a safe haven for the likes of Farquhar and Moore-Martin, but Field had wormed his way into their lives and hearts, and the consequences were devastating.

The case was previously covered in Channel 4's Catching a Killer documentary series in 2020, but it has all of the ingredients for a compelling dramatic adaptation and as such, it was only a matter of time before it was given that treatment. But even when a true crime story is told with the best of intentions, which this absolutely was – "The victim is always the most important element," said writer Sarah Phelps. "One thing I didn't want to do was to glamorise the killer" – by its very nature the perpetrator is the most enthralling aspect.

Within the parameters of entertainment, the victim or victims are secondary to The Thing that has been done to them, and how the offender was able to get away with it for as long as they did. Although broadcasters and streamers will talk of the moral motivations to share these stories, they also know that fear sells.

Phelps emphasised that the "backstories" of Farquhar and Moore-Martin were "really important" to her and through her writing, we get a real sense of who they were before Field infected them – their "full, vibrant, intelligent, educated lives (they were both retired teachers) full of curiosity with families, friends". But regardless of intent, that isn't why the vast majority of the public watch true crime.

Like all those of his ilk, Field has a subhuman quality to him. His wicked behaviour, all of which was premeditated to the nth degree, isn't something that any ordinary person can wrap their head around. We will never understand how a person can be so nasty, so ghoulish and as such, they are the central draw, even with the steps taken to foreground Farquhar and Moore-Martin. If we come away remembering the names of those who were harmed and gain an appreciation of who they were as people, that's a mark of good and responsible storytelling, but Field is the subject we want to read about afterwards.

Even after watching an extensive account of what he did, our morbid curiosity is often not satiated – cue the multitude of articles about his current whereabouts, his childhood, what cereal he ate. Cue the online search demand for photographs of him, both solo and with Farquhar and Moore-Martin, photos of his cluttered flat, his mirror messages, any morsel from his life – which Field himself will undoubtedly enjoy.

Part of the allure for people like him is the notoriety, to remain relevant and be talked about en masse. His scheming was brought to an end by a suspicious relative and the police, but not before he flexed his muscles to full effect.

It is one of life's uncomfortable truths, but it's also instinctive to want to understand why people do the things they do, to climb inside their mind and uncover what's lurking there. I attended a Q&A with a criminal psychologist a number of years ago and she said that it's also linked to self-preservation – in layman's terms: here's what to look out for so that that we, the viewer, do not find ourselves the subject of our own true crime series.

Phelps did talk about the public service that The Sixth Commandment could provide – "We need to look more closely at the people we think we know and realise so many are vulnerable... we need to be more vigilant about the people who come into our lives." But even then, that doesn't do anything to tackle the inherent problem with true crime.

There's also the finishing touches – the unnerving score, a threatening face cast in shadow, "scenes created for dramatic purposes" – which often leaves me thinking: Isn't the real-life case dramatic enough without the additional bells and whistles?

The Sixth Commandment is an excellent piece of television with noble intentions and, crucially, the full support of the victims' families, which is of paramount importance when telling these types of stories. But regardless, it remains tethered to the murkier aspects of the genre.

The Sixth Commandment airs on BBC One and BBC iPlayer. Check out more of our Drama coverage or visit our TV Guide and Streaming Guide to find out what's on.

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