‘In the green room I was hanging out with all the other killers,’ reminisces actor Joseph Simpson-Bushell. ‘I remember Peter Sutcliffe, Dennis Nilsen and myself – Ian Huntley – all getting on like a house on fire.’

It’s November 2016 at County Hall in Kingston-upon-Thames, where a courtroom was being used to film episodes of the documentary series Britain’s Most Evil Killers. The reconstructers act as a visual aid, but their lack of lines limit them to an extra’s pay – only £200 a go, another re-enactor recalled, which isn’t a great rate to impersonate some of the worst people alive (or dead).

These low-budget enterprises generate their own surreal scenes, with locations often hired to film back-to-back episodes at a time, actors waiting together in sinister attire. One imagines Myra Hindley taking fag breaks with Fred West. Levi Bellfield making a cuppa for Beverley Allitt. Stephen Port doing TikTok dances in the car park with Jeremy Bamber. All in a day’s work for a jobbing actor, but for passersby, it must look like a psychopaths’ comic-con.

How do you get into this, exactly? How do you break into the ‘professional serial killer cosplay’ scene? Well, there are casting calls, obviously, for those eager to enter television heaven from the purgatory of background work and dull commercials.

Appearance is key. When auditioning to play Dennis Nilsen, Luke Ireland did not let the hurdle of physical dissimilarity stop him from embodying Scotland’s most famous necrophile civil servant. Eager to land the role, he sourced his own outfit, complete with Nilsen’s signature metal glasses. Another actor, David Wayman, recalls one obsessive producer of a Harold Shipman re­enactment haranguing him for ‘photos of progress’ of his facial hair. Having shaved off his beard to film Shipman’s youth, scheduling issues forced Wayman to don an itchy false beard through the rest of production.

Other actors are fortunate enough to already resemble the murderers they portray. What could be a horrifying doppelgänger nightmare in real life can provide steady work if you know the right casting agents. ‘I applied for a role in a drama reconstruction, not knowing who it was portraying,’ Kathryn Mincer says.

‘I just knew they needed a brunette of a certain age. That was how I got into playing Joanna Dennehy’ – the spree-killer who in 2013 murdered three men, stabbed two more and stole a dog.

From books to walking tours, conventions to social media detectives, we are obsessed with what makes a killer. True crime is ubiquitous and, given its profitability, is likely to remain so. The company behind the Serial podcast sold for $25 million to the New York Times in 2020, while the My Favourite Murder true crime comedy podcast has spawned live shows, a legion of dedicated listeners known as ‘Murderinos’ and a bestseller titled Stay Sexy and Don’t Get Murdered.