How a quiet hero tracked down The Serpent, the world’s most-wanted serial killer

Guy Kelly
·20-min read
Charles Sobhraj (centre) the now 76-year-old Frenchman variously known as the Bikini Killer, and the Serpent - Cristiana Couceiro
Charles Sobhraj (centre) the now 76-year-old Frenchman variously known as the Bikini Killer, and the Serpent - Cristiana Couceiro

Forty years ago, the Canadian criminal psychologist Dr Robert Hare drew up an innovative checklist to determine whether or not a person is a psychopath. Among some 20 traits, he included pathological lying, glib and superficial charm, a grandiose estimation of self, juvenile delinquency, sexual promiscuity, criminal versatility and, of course, a lack of remorse.

It isn’t known whether Charles Sobhraj, a now 76-year-old Frenchman variously known as the Bikini Killer, the Splitting Killer and the Serpent, who murdered at least a dozen young people across South Asia in the 1970s, evading capture for so long he became Interpol’s most-wanted man, has ever taken Hare’s test. But to Herman Knippenberg, the man who eventually halted Sobhraj’s reign of horror, that doesn’t matter. He is convinced.

‘Sobhraj is just absolutely a psychopath. He fits all the criteria. Every single one,’ Knippenberg says, emphatically. He repeats one particular characteristic with gusto. ‘A total. Absence. Of empathy.’

The twisted, grisly and at times absurd tale of Charles Sobhraj isn’t widely known in Britain. In France, though, where he was born and where (after one prison release), he lived as a despised but swaggering public figure, or southeast Asia, where he committed many of his known murders, or India, where he served a 20-year prison sentence, or Nepal, where he is currently pent up on a life term, his case is as infamous as that of any serial killer.

Herman Knippenberg photographed in Wellington, New Zealand, November 2020 - Victoria Birkinshaw
Herman Knippenberg photographed in Wellington, New Zealand, November 2020 - Victoria Birkinshaw

On New Year's Day, a stylish new BBC and Netflix miniseries, The Serpent, reintroduced Sobhraj to Western audiences. Five years in development and filmed on multiple continents either side of the global shutdown, it comes from the producers behind Victoria, the writer of Ripper Street and the director of The Missing, and stars the celebrated French actor Tahar Rahim in the title role, along with Jenna Coleman as his Quebecois fiancée and accomplice, Marie-Andrée Leclerc, plus Ellie Bamber and Tim McInnerny.

Over eight episodes, the series shows how Sobhraj – posing, principally, as a harmless gem dealer – beguiled, duped and slaughtered his way around the hippie trail of Asia in the 1970s. But as much as he would love to be the star, Tom Shankland, the director, and Richard Warlow, the lead writer, deliberately eschewed that path. Instead, the narrative is driven by Knippenberg (played by British actor Billy Howle), the quiet Dutch diplomat whose dogged investigation into Sobhraj left the two inextricably linked.

‘Charles was this lizard king, the chameleon embodiment of the ’70s, but what fascinated me was the match-up with Herman, a man who might celebrate – to use the vernacular of the times – “squarer” virtues of diligence, decency and compassion,’ Warlow says.

Knippenberg and Shankland started emailing in 2015, but the director came across the legend of Sobhraj when he was 18, travelling in Nepal in the 1980s, and was told about ‘a gentleman and his girlfriend with a gang who’d lure hippies to their doom’. He remembered it again seven years ago and, after more digging, discovered there was a cat-and-mouse game involved. And the cat, Knippenberg, was just as interesting as the mouse.

Tahar Rahim and Jenna Coleman in The Serpent - BBC/Mammoth Screen
Tahar Rahim and Jenna Coleman in The Serpent - BBC/Mammoth Screen

Knippenberg is now 76, and lives in Wellington, New Zealand, the site of his final, four-year posting (he retired in 2003, after three decades in the foreign service). He lives there with his second wife, Vanessa, a Kiwi, and spends his retirement ‘in essence reading, watching movies, and in the morning I do one hour of speed-walking for six kilometres’. An affable and warm presence on the telephone, Knippenberg’s prodigious memory means he can recall, with remarkable precision, all the knotty events of his posting to the Dutch embassy in Bangkok in the mid-1970s.

He was 31 and on his first major foreign posting when he arrived, with his first wife Angela (played by Bamber in the series), as the third secretary at the embassy in Thailand in 1975. A doctor’s son from the east of the Netherlands, at the time he was ‘a bit of a gopher’ – his in-tray tending to include commercial trade hiccups, the odd passport dispute and mountains of paperwork.

Occasionally, a young tourist from the Netherlands would go off the map. This being southeast Asia in the mid-1970s, these tended to be hippies (or ‘longhairs’, as they were dismissively referred to in Bangkok’s diplomatic circles), who wandered off their eponymous trail and forgot to write home to their parents.

That was the embassy’s initial assumption in February 1976, when Knippenberg was asked to look into the case of a missing Dutch couple, Henk Bintanja and Cocky Hemker. ‘They had not written in six weeks, and over Christmas. I thought, “Something is wrong here,”’ Knippenberg recalls. ‘But I thought maybe they’d lost a passport or gotten sick and were stuck somewhere in the jungle.’

A briefing note from one of the missing travellers’ parents claimed the pair had met ‘a Frenchman, a dealer in precious stones’, who had invited them to stay with him in Bangkok. This wasn’t necessarily cause for alarm, but the notion of a shady Frenchman recurred when a Belgian diplomat friend of Knippenberg told him about two Dutch passports seen in a flat owned by a Frenchman of mixed Vietnamese and Indian descent, who was rumoured to have murdered several backpackers.

9 April 1997: Sobhraj enjoying reading about himself back in Paris after his release from jail in India - Shutterstock
9 April 1997: Sobhraj enjoying reading about himself back in Paris after his release from jail in India - Shutterstock

When he heard this, Knippenberg recalled a gruesome newspaper article two months earlier about an Australian couple whose murdered, charred remains were found on a roadside in Thailand. Two details in the report had struck him: the T-shirt the woman was wearing had been produced in the Netherlands, and they had arrived in Thailand via the ‘hippie trail’ from Europe.

The bodies, he soon discovered, had only ever been informally assumed to be Australian, so he organised to have them identified. At the police morgue, he arrived to find a Dutch dentist craned over the bodies.

‘She turned and said, “Mr Knippenberg, it’s them!” They had been strangled, then burned, then somebody had opened them up in the chest and stitched them back together with telephone wire after the autopsy. I tell you, I am not easily flushed, but I gasped. And my Thai driver, a former policeman, fainted,’ he remembers. Another pathologist told him about the cause of death. ‘That was what shocked me out of my wits. He said there was soot in the lungs, which meant they had been set on fire when they were still breathing.’

Inadvertently this mild-mannered young diplomat had stumbled on the trail of a murderer. What he didn’t know was that the killer in question, Charles Sobhraj, had already claimed at least five victims. Working with his relentlessly loyal girlfriend, Leclerc, 31, and principal acolyte, Indian Ajay Chowdhury, 22, he had spent the better part of a year moving around southeast Asia, luring wide-eyed beatniks into his web, ostensibly as a gem dealer but promising his quarry far more, in the form of shelter, drugs, connections and parties. Some of them he would go on and kill.

Henk Bintanja and Cornelia ‘Cocky’ Hemker, the Dutch couple murdered by Sobhraj in Thailand - Shutterstock
Henk Bintanja and Cornelia ‘Cocky’ Hemker, the Dutch couple murdered by Sobhraj in Thailand - Shutterstock

Even by the standards of pathological 20th-century serial killers, Sobhraj is a mystifying character. Born in Saigon, but sent to boarding school in France, his father was an Indian tailor and his mother, a local Vietnamese woman, was his father’s mistress. As a teenager, he fell into petty crime, but using his charm, good looks and smarts, manipulated his way out of any punishment.

Shortly after marrying a French woman, Chantal Compagnon, who became pregnant with his daughter, he fled an arrest warrant by travelling to the Middle East and Asia in 1970. There, he sank further into crime, making vast amounts of money through theft and smuggling. In Mumbai, where he came to know the black market intimately, he was arrested for armed robbery but escaped jail, with Compagnon’s help, by faking an illness.

The charisma, opportunism and slipperiness were still present in Sobhraj when he began feeding on the hippie trail in 1975. On the run from authorities in India and Afghanistan – variously, for car theft, holding a flamenco dancer prisoner, and drilling into a gem store to steal thousands of pounds worth of precious stones – he found peace-loving drifters to be easy targets. To him, they were gullible, impressed by his confidence and six languages, dazzled by the gems he dealt, and open to giving him anything – money, passports, loyalty, sex. Sobhraj utterly despised them as spoiled, drug-addicted hypocrites.

Shankland, who filmed the bulk of The Serpent on location in Thailand, compares Sobhraj to Charles Manson, another who inveigled young hippies into his den.

‘Individuals who have the desire and ability to spin yarns that draw people into their truth are fascinating. It’s why we go back to stories like Manson, who was committing crimes at about the same time as Sobhraj,’ he says. ‘There’s something poignant and disturbing about hippies’ innocent, hopeful vision of the world, and what happens when that meets an uber-cynical, self-serving, f—ed-up character who preys on it.’

Sobhraj and his lover Leclerc in the 1970s - Shutterstock
Sobhraj and his lover Leclerc in the 1970s - Shutterstock

By August 1975, Sobhraj had his accomplices, Leclerc and Chowdhury, in place. He’d met, and charmed, Leclerc when she was travelling in India. They were lovers but soon also partners in crime: she could pose as his wife, or a nurse, or a model (he would occasionally pretend to be a photographer). Chowdhury, meanwhile, who Sobhraj picked up in a park in New Delhi, became a factotum, as much bag carrier as confidant and heavy.

Though he kept an apartment in Bangkok, Sobhraj and his small gang moved a lot, and he employed various aliases, often Alain Gautier, when he collected lost-looking beatniks around Thailand. A frequent ploy involved drugging his victims, with the help of Leclerc and Chowdhury, using a gruesome cocktail of chemicals – laxatives, Quaaludes, ipecac – to incapacitate them while he copied their passports or robbed them blind.

Over the next nine months, he began murdering. A few were drowned, such as one of his earliest victims, Theresa Knowlton, a young American, who in her drugged stupor was undressed, redressed in a bikini, then left to drown off a beach in southern Thailand in 1975 (hence the ‘Bikini Killer’). Others were drowned in the bath, or beaten, or stabbed, or strangled or, as Knippenberg would come to discover, set on fire.

‘Contrary to what is generally said, which is that the ones killed were the weak ones in his “surrogate family”, in actual fact they were the strong ones.’ says Knippenberg. ‘They were the people who refused him, who had something he wanted but he couldn’t get.’

This was the 1970s, a time when the region was largely unregulated and run, in the main, by easily corruptible police. It is how Sobhraj, Leclerc and Chowdhury were allowed to freewheel around, unchecked. Local authorities didn’t believe a foreigner could be a psychopathic serial-killing gem dealer or they were easily fobbed off by one of Sobhraj’s old tricks.

Herman Knippenberg with actor Billy Howle - BBC
Herman Knippenberg with actor Billy Howle - BBC

Over the course of weeks and months in 1976, Knippenberg urged the authorities to investigate the ‘Frenchman’ who the murdered Dutch couple had stayed with. A raid on Sobhraj’s Bangkok apartment was ordered, which came to nothing; the Thai police let him go when he produced an American passport and claimed to be from Puerto Rico.

That night, Knippenberg lay awake pondering some more. ‘Suddenly I turned to my wife and said, “Eureka! I’ve got it! The Americans!” If he had an American passport, he must either be American or he had killed an American and taken their passport. My hunch was the second one.’

His hunch was right, of course. Sobhraj had killed Americans, all right, not least Knowlton, and had probably robbed dozens more. Six weeks after that raid, Knippenberg and his so-called ‘action committee’ of allies – which included a neighbour of Sobhraj, Nadine Gires – were allowed into Sobhraj’s apartment. They found passports, drugs, handcuffs – all the evidence they needed. But Sobhraj had long escaped abroad.

Knippenberg, meanwhile, was becoming increasingly obsessed with Sobhraj. Piles of manila folders amassed at work and home. He would spend every waking moment thinking about Sobhraj’s next move. While he claims not to have feared somebody would come for him, friends did gently suggest he was in too deep. One night, that stress-induced jitteriness resulted in him pulling a gun on his own wife, who he believed was an intruder. ‘It was the only time I felt really fearful. I almost exploded. I realised, because of the reaction I made, that I was now in a very dangerous situation,’ he says.

Despite cracking the case, his only real hope of seeing his foe behind bars was to trust that, somewhere in the world, he would bite off more than he could chew. That came in July 1976, when Sobhraj attempted to drug 22 members of a French tour party in a New Delhi hotel lobby, presumably in order to rob them. Some of the group stayed awake and alerted the authorities, who apprehended Sobhraj and jailed him for 12 years for the manslaughter of two tourists. Leclerc was arrested two days later.

‘I think, in essence, his downfall is that he is the born gambler,’ says Knippenberg. ‘This is in line with Nietzsche, that the only thing in life is to live as dangerously as possible – the tightrope-walker, building your house on the slopes of Vesuvius. So you push your luck as far as you can because you are different.’

Charles Sobhraj is released from Tihar jail in New Delhi, 19 February 1997 -  shutterstock_editorial
Charles Sobhraj is released from Tihar jail in New Delhi, 19 February 1997 - shutterstock_editorial

Threading these events – plus all Knippenberg’s investigative detail, let alone what Warlow describes as Sobhraj’s ‘web of bullshit’ – into a coherent narrative for television was no small task. Fortunately, they had Knippenberg. ‘Herman’s incredible,’ Warlow says, ‘he loves theatre, and would come to London to watch plays, travelling via Bangkok and Europe, then he’d turn up at our production offices with two tote bags full of lever-arch files containing notes and documents, and he’d know exactly where everything was.’

Warlow let not only Knippenberg see the scripts, but also Angela, Nadine Gires, and relatives of Theresa Knowlton. Where possible, too, the cast met their characters. Howle, whose task was to capture a 31-year-old Knippenberg, was particularly appreciative. ‘Herman had almost forensic recollections of everything, which I found really useful,’ he says. It was the first time he’d played a real-life person. ‘It’s a huge mantle of responsibility, but I kept reminding myself that it’s nothing compared to what Herman actually went through.’ They spoke several times, but didn’t meet until filming was underway in Bangkok in 2018.

Knippenberg is delighted with the series. ‘Oh, you are in for a treat!’ he exclaims. He is also exultant about Howle’s portrayal (when Knippenberg and I speak, he is about to ‘send a small e-card to Billy’ for his 31st birthday). Over the years, several books and documentaries have been produced about Sobhraj, but this is the first time Knippenberg has collaborated on a screen adaptation.

The other side of the story, of course, is Sobhraj’s. And it doesn’t end with that arrest in New Delhi. In the city’s Tihar jail, he became king of the castle, manipulating both guards and fellow inmates alike. To win over the former, he strapped a tape recorder to his thigh, then secretly recorded conversations he’d had with staff, in which they admitted they were corrupt. He then took the tape to the superintendent in charge and said, ‘I am a criminal and you are a criminal, so we should cooperate.’

It worked. He received luxury items like a colour television and portable typewriter and, according to one guard, could have sex with Leclerc twice a week in the superintendent’s office. He was safe in the Indian judicial system; so safe, in fact, that when his sentence was nearing completion, he deliberately escaped from jail (by pretending it was his birthday, poisoning the guards with celebratory snacks, then driving out of the compound) in order to be captured again and given another 10 years. The alternative, as he well knew, was extradition to Thailand, where he would almost certainly have been killed.

By 1997, the Thai arrest warrants had lapsed, meaning Sobhraj, despite repeatedly discussing his murders, became a free man aged 52. Leclerc was released from prison in New Delhi in 1983 and allowed to return to Canada on account of having been diagnosed with ovarian cancer. She died the following year. Chowdhury has never been caught.

Charles Sobhraj, escorted by Nepalese police, following a court hearing in Kathmandu, 31 May 2011 - Narendra Shrestha/EPA/Shutterstock
Charles Sobhraj, escorted by Nepalese police, following a court hearing in Kathmandu, 31 May 2011 - Narendra Shrestha/EPA/Shutterstock

Sobhraj returned to Paris, where he marinated in life as a quasi-celebrity, at once reviled and given constant attention from people fascinated by his story. He posed for newspapers, charged $5,000 to lunch with fans, gave interviews, appeared in documentaries and negotiated movie deals.

Then, in 2003, he made the bewildering decision to travel to one of the few countries in which he could be arrested, Nepal. Knippenberg’s tightrope-walker theory was reproven: Sobhraj couldn’t resist the greatest risk. He was recognised, arrested in a casino, and – with the help of Knippenberg’s decades of evidence – sentenced to life. In 2014, a further 20 years was added. But he remains comfortable and has remarried (it isn’t fully known how many wives or children he has had), this time to Nihita Biswas, the daughter of his lawyer. She is four decades his junior and once appeared on the Indian reality show Big Boss.

Knippenberg has never fully let go of the case, despite moving from Thailand to other diplomatic jobs in the US, Indonesia, Austria, Luxembourg, Greece and New Zealand – as well as completing a Master’s in leadership theory at Harvard, focusing, yes, on the tactics of charismatic figures like Sobhraj. And through it all, the cat and mouse never met. ‘I don’t know what he has against me,’ Sobhraj once said of his hunter.

‘It is a double-edged sword,’ Knippenberg says. ‘It comes down to the question, “Do I admire the man?” And no, I do not. I am fascinated by him, but only as I am fascinated by a tarantula or a saltwater crocodile… One of Sobhraj’s favourite sayings is, “If you feel the heat, go straight into the kitchen.” To a certain extent I agree, but to have drinks with the man? This goes too far.’

At this moment, I put to him, Sobhraj is locked up, you got your man, and the world is about to know your quiet hero’s story. The case is closed, isn’t it?’ Knippenberg sounds as if he’s stifled a laugh: ‘Oh, the Sobhraj case doesn’t close until he is in a better world and the Lord deals with him. And if there is such a place, He will have to be stern.’

The Serpent continues every Sunday at 9pm

How it unfolded: a timeline 

6 February 1976 – Herman Knippenberg, a junior secretary at the Dutch embassy in Bangkok, opens his post and reads he has been tasked with locating two missing Dutch travellers, Henk Bintanja and Cocky Hemker. Letters to their families show they had met a shady Frenchman, who had invited them to stay at his apartment.

3 March  – After deciding to investigate whether the  burned corpses of two tourists, previously  believed to be Australian, could be his missing  Dutch couple, Knippenberg has them identified  and discovers his hunch was correct. 

6 March – Having built an initial case, including identifying the Frenchman as Alain Gautier, Knippenberg finds a witness, Nadine Gires, who lives in the same building as ‘Gautier’. Gires confirms the couple visited the apartment and that ‘Gautier’ was an alias of Sobhraj, who had spent most of the past year poisoning, robbing and even murdering backpackers. 

11 March – A police raid is ordered on Sobhraj’s flat, but he is let go after pretending to be an American, presenting one of his stolen passports to prove it. A secondary search, conducted by Knippenberg and his allies, finds incriminating evidence supporting his developing theory that Sobhraj is a serial killer.

5 July  – After going on the run for months, Sobhraj is finally arrested for trying, and failing, to poison dozens of French students in a hotel lobby in New Delhi. He is sentenced to 11 years in Tihar prison in New Delhi.

1987 – Knowing he would be extradited to Thailand, where he’d probably be executed for his crimes, Sobhraj drugs his guards, escapes for a month, and receives another decade in his comfortable Indian jail. 

1997 – Finally released and his Thai arrest warrant lapsed, Sobhraj lives as a kind of celebrity in Paris, charging journalists for interviews, striking movie deals and possibly returning to black-market dealings.

2003 – Sobhraj makes the curious decision to travel to Nepal, one of the few countries in which he could still be arrested. He is spotted and sentenced to life. In 2014, he is given a further 20 years when he is convicted  of another murder. There, aged 76, he remains.

The key players

Charles Sobhraj played by Tahar Rahim

A psychopathic French-Vietnamese serial killer, jewel thief, escape artist and, latterly, self-publicist.  In 1975, as he swept around South Asia collecting  hippies as acolytes, he is believed to have committed  at least 12 murders.

Charles Sobhraj  played by  Tahar Rahim - BBC
Charles Sobhraj played by Tahar Rahim - BBC

Herman Knippenberg  played by Billy Howle

The quiet, persistent Dutch junior diplomat who was on his first foreign posting in Bangkok in 1975 when  he stumbled into the web  of Charles Sobhraj and  decided to pursue him.  He didn’t give up until he had his man – decades later.

Herman Knippenberg  played by  Billy Howle - BBC
Herman Knippenberg played by Billy Howle - BBC

Ajay Chowdhury played by Amesh Edireweera

Sobhraj’s accomplice in at least eight murders, who he met in a New Delhi park in 1975. Sobhraj would dispatch Chowdhury, who could pass for ‘hip’, to find ‘customers’ at hotels. He’d lead them to ‘his boss’, then help poison, rob or kill them. He was never arrested and was last heard of in Frankfurt in 1977.

Ajay Chowdhury  played by  Amesh  Edireweera - BBC
Ajay Chowdhury played by Amesh Edireweera - BBC

Marie-Andree Leclerc played by Jenna Coleman

The French-Canadian was on a three-week holiday to India when she met Sobhraj in May 1975, abandoning the friend she was travelling with to begin a relationship with him. Fiercely devoted, she bought into his life of crime, frequently assuming a fake identity so people would trust him. Stayed loyal until her death in 1984.

Marie-Andree Leclerc  played by  Jenna Coleman
Marie-Andree Leclerc played by Jenna Coleman

Nadine Gires played by Mathilde Warnier

A 21-year-old French woman who became Sobhraj’s neighbour in Bangkok and quickly got to know his inner circle. She grew suspicious and later became a crucial witness for Knippenberg and investigators, keeping tabs  on the group and giving evidence. She visited the set of The Serpent.

Nadine Gires  played by  Mathilde  Warnier - BBC
Nadine Gires played by Mathilde Warnier - BBC