Few documentaries have made as big a splash as The Tinder Swindler, the story of an online dating scammer, Simon, and three of the many women he conned out of huge amounts of money.

When the true crime feature came out last year, it was the most-watched feature documentary in Netflix’s history, notching up 166 million views in its first month.

The Tinder Swindler deservedly won its director and writer, Felicity Morris, a Bafta but no one, including Morris, would deny that the real stars of the show are Cecilie, Pernilla and Ayleen.

The three women who, between them, lost hundreds of thousands of pounds and braved public humiliation by revealing how Simon, posing as an Israeli diamond dealer and international playboy, won their affection and then rinsed them for every penny they owned or could borrow.

It is a riveting film, which revolves around three lengthy interviews with the women and is peppered with the WhatsApp messages they sent to and received from Simon, a man so reptilian that even his mum disowned him.

At an RTS Futures event in July, Morris, Cecilie Fjellhøy – a Norwegian serial Tinder dater based in London – the film’s producer, Bernadette Higgins and editor Julian Hart revealed how they made The Tinder Swindler.

“None of us would have known about the story had it not been for Cecilie,” said Morris.

When the penny finally dropped that Simon was a scammer, Fjellhøy took her story to VG, a Norwegian newspaper based in Oslo, determined that no more women would be taken in.

VG spent months researching the story and published an in-depth investigation. It came to the attention of London production company Raw, which began developing a documentary feature; Fjellhøy and Pernilla Sjöholm were the key contributors. The latter was a friend rather than girlfriend, yet still fell under Simon’s spell.

Usually, documentaries are made after the events they’re portraying have played out, but Simon, having been identified as a conman and off Tinder, was still on the run. “When we started, we had no idea where the story would end,” said Morris.

In fact, the film was being edited when the programme-makers found their ending by persuading one of Simon’s victims, who had taken satisfying revenge on him, to participate. “We were in the edit when Bernie [Higgins] finally managed to convince Ayleen to be in the film… that gave us an ending that, if you’d been in a writers room, you couldn’t have come up with anything as good,” revealed Morris.

The story “reads like a Hollywood script”, said Higgins. “Cecilie and Pernilla were such brilliant storytellers and so engaging – [we knew] we had to tell this story to understand how something like this unfolds and make people understand that it really can happen to anyone

“We’ve all heard about elderly people being defrauded at home or of desperate people… but, before the Tinder Swindler, we hadn’t really heard stories about young, professional, educated, cosmopolitan women who had had the wool pulled over their eyes.

“There is a scam for everyone and these guys know how to spot people’s vulnerabilities… everyone is vulnerable in some way.”

Fjellhøy’s motivation for appearing in the programme was twofold: “Simon was still out there – he hadn’t received the kind of justice that I felt that he deserved [and] I didn’t want anyone else to go through what I had been through.”

It was a brave and selfless decision – after VG published its investigation, Fjellhøy was subjected to vicious social media trolling and ridiculed for her supposed naivety.

For the film, Fjellhøy was interviewed by Morris over two long days, which she freely admits was hugely upsetting. “What was most difficult for me was that I had to go through very loving feelings; the worst was having to revisit the kiss.… It was so disgusting having to talk about the first kiss with a person that you absolutely hate right now.

“It was a roller coaster of emotions, but I knew it was important and I needed to get through it.… It was painful to see myself cry [on screen].”

Editing the film was a complex and lengthy process; Fjellhøy’s interview alone ran to nine hours. “That is actually a good sign because it means there’s lots of good stuff – the interview with Cecilie was really strong, as they all were,” recalled Hart.

“You cut it down,” he explained, while keeping the key “information and emotion”. Hart added the WhatsApp messages between Simon and his victims to enrich the story. To provide atmosphere, archive film was added from movies such as Disney’s Beauty and the Beast and Charade, starring Cary Grant and Audrey Hepburn. The latter, explained Hart, was free to use “because someone fucked up” with the rights in 1963, when it was released.

Thanks to the efforts of another of the swindler’s victims, Dutch woman Ayleen Charlotte, Simon is punished, to a degree, for his crimes. To enjoy his comeuppance – and they will – viewers will have to watch The Tinder Swindler.

Does Fjellhøy feel justice was done? “In the sense that everyone knows him for what he is – and he’s very angry at us – which I’m very happy about. But it has been disappointing [to see] the lack of action by the European police… they should be ashamed.”

But Fjellhøy had nothing but praise for another oft-criticised profession. “Thank God for journalism – no one took us seriously until I contacted journalists… then someone truly listened to me and my story.”

Working with the Norwegian newspaper and the film-makers at Raw, she said, had “been healing… I had to think about what I did and what he did to me”.

Since the film’s release, Fjellhøy says her life has become “very weird”. She has told her story widely and is launching a charity to support the victims of fraud and help build their resilience.

Fjellhøy has received many messages of support and gratitude, which has been hugely beneficial, but emphasised the “emotional pain [Simon] put on his victims, the emotional abuse and the horrible, horrible treatment of us”. He remains at liberty in his native Israel and is still active on social media.

Report by Matthew Bell. The RTS Futures event ‘Anatomy of a hit: The Tinder Swindler’ was held at the London Transport Museum on 13 July. It was hosted by the broadcaster Yinka Bokinni and produced by Michael Fraser and Rajveer Sihota.