How A Dutch Diplomat And His Wife Helped Find The 'Hippie Killer,' The Real Man Behind 'The Serpent'

Authorities believe that Charles Sobhraj - the man known as the "Hippie Killer," “The Bikini Killer,” and "The Serpent" - murdered a dozen people between 1972 and 1976. Sobhraj was known for befriending tourists in various countries, then drugging or poisoning them. He developed crime rings across Europe and Asia, always evading police. Even when he was arrested and sent to prison, Sobhraj managed to break out multiple times. 

In an unexpected turn of events, a young Dutch diplomat named Herman Knippenberg laid the groundwork that eventually brought Sobhraj to justice. Here we'll explore how Knippenberg's determination to solve the murders of two Dutch tourists led to the capture of one of the most notorious serial killers of the 1970s.

  • In February 1976, Dutch Diplomat Herman Knippenberg Received A Letter About Two Missing Backpackers

    Herman Knippenberg was a 31-year-old junior diplomat at the Dutch embassy in Bangkok, Thailand, when he received an urgent letter from a man in the Netherlands on February 6, 1976. In the letter, the man stated that his sister-in-law and her boyfriend had traveled to Thailand but had seemingly gone missing. 

    The couple, Cornelia “Cocky” Hemker and Henricus “Henk” Bintanja, had been writing to their family twice a week during their trip across Asia in late 1975, but they hadn't made any contact for six weeks. 

    By early March, Knippenberg had connected the disappearance of Hemker and Bintanja to an unsolved murder just 50 miles north of Thailand.

  • Knippenberg Connected The Names To Two Charred, Unidentified Bodies Found Weeks Prior

    On December 16, 1975, two badly burned bodies were found along a road known as the “hippie trail” near the Thai city of Ayutthaya. The bodies were burned beyond recognition, but a coroner determined that the victims were still alive when they had been doused in gasoline and set on fire. 

    Herman Knippenberg had heard about the charred corpses before receiving the letter about Hemker and Bintanja, and he began investigating whether or not the two cases were related. Knippenberg obtained the couple's dental records, and on March 3, 1976, a Dutch dentist determined that Hemker and Bintanja were indeed the murder victims.

    Knippenberg later recalled that day in the morgue, saying, “I had the feeling that I was stepping outside of myself - that I'm on the side, watching the scene.”

  • A Friend Told Knippenberg About A Gem Dealer Whose Bangkok Apartment Was Filled With Missing People's Passports

    Prior to investigating the murders of Hemker and Bintanja, Knippenberg had a conversation with a friend about stolen passports. The friend, Paul Siemons, worked at the Belgian embassy and had heard about a French gem dealer by the name of Alain Gautier living in Bangkok, who had a large number of stolen passports in his apartment. Specifically, Siemons remembered that Gautier had two Dutch passports in his possession.

    Although Siemons did not want to reveal how he had found out about the stolen passports, he eventually told Knippenberg to visit a woman named Nadine Gires, a neighbor of Gautier. Knippenberg would eventually learn that Alain Gautier was merely an alias for Charles Sobhraj, a French criminal who committed serial killings across Asia.

  • Authorities Took Charles Sobhraj In For Questioning, But He Was Ultimately Released

    When Knippenberg went to interview Nadine Gires, he learned that Sobhraj had a number of people working with him in a crime ring, and many believed Sobhraj had committed murder to acquire the stolen passports. 

    Upon learning that Sabhraj and his girlfriend/accomplice, Marie-Andrée Leclerc, were making plans to flee Thailand for Europe, Knippenberg had police arrest Sobhraj and take him in for questioning. However, Sobhraj had a passport indicating that he was a United States citizen, and Thai authorities subsequently released him. 

    Investigators later discovered that Sobhraj had used one of his victims' passports and put his own photo inside to evade law enforcement.

  • Nadine Gires, Sobhraj's Neighbor, Smuggled Passports Out Of His Home To Give To Authorities

    Nadine Gires called Knippenberg the night after Sobhraj's arrest to tell him that she had been invited over to Sobhraj's apartment. She knew another accomplice would be there, and she feared for her safety, having aided in Sobhraj's arrest. Despite her fears, Knippenberg urged her to go so as not to raise suspicion. 

    Fortunately, Gires was able to get out of the apartment safely. In fact, she was able to slip several passport photos into her bra when no one was looking. 

    Although police now had physical evidence that tied Sobhraj to several missing persons, he managed to leave Thailand without a trace.

  • Sobhraj Went On The Run, Amassing A Group Of Loyal Accomplices Along The Way

    Following his arrest by Bangkok police, Charles Sobhraj fled to Malaysia with Leclerc. Sobhraj had accomplices across Asia, and they would introduce him to tourists whom he would then drug, rob, and murder. 

    Those who aided Sobhraj were often tricked into doing so. For example, he earned the trust of two French police officers after helping them track down their missing passports, even though authorities later discovered that Sobhraj himself had stolen them. He also aided a tourist who believed she had dysentery, but she later learned Sobhraj had poisoned her.

    Even when Sobhraj was in Tihar prison in India, guards and fellow inmates feared him. He was able to have special meals prepared and move freely throughout the prison by recording conversations with guards that he used as blackmail. He also wrote court petitions on behalf of fellow inmates to earn extra money.