In February 2016 at Stockholm’s District Court, 38-year-old Dr. Martin Trenneborg was jailed for 10 years after kidnapping a woman and holding her captive for six days in a purpose-built underground concrete bunker at his isolated home. The doctor, who trained at the award-winning Karolinska Institute in Stockholm and worked as a general practitioner, is believed to have spent years building the sound-proof bunker at his house in Kristianstad in southern Sweden.

Tenneborg's isolated home with purpose built bunker

Trenneborg’s isolated home with purpose-built bunker (front left).

In echoes of the Austrian Josef Fritzl case, who imprisoned his daughter in a dungeon underneath his house for 24 years, Trenneborg had built multiple rooms, a bathroom and installed electronic locks throughout in what prosecutors said was intended to be the long-term home of women he planned to kidnap.

Trenneborg met his victim, who used the name Isabel Eriksson in interviews to protect her real identity, according to the Mail Online, at her apartment in Stockholm. On 12 September 2015, he drugged her with Rohypnol laced strawberries rendering her unconscious and allowing him to take her to his car and drive the 342 miles to his home. Trenneborg is believed to have worn two different rubber masks during the drive to ensure he wouldn’t be recognized, masks that were later found inside his residence. He also injected his victim hourly with more drugs, making sure she stayed sedated throughout the seven-hour drive.

Martin Trenneborg

Martin Trenneborg

I remember that he fed me strawberries. That I do remember. It is very hard to talk about. But after that I fell asleep everything was completely black,” Eriksson told Swedish Television after her ordeal. “He said that he has kidnapped me and will have me locked up for a few years,” she continued.

After six days on 18 September 2015, Trenneborg returned to Stockholm to pick up some of Eriksson’s belongings from her apartment. When he arrived he discovered she had been reported missing to police, a fact that clearly unnerved him. Back at Kritisnstad, he took Eriksson out of the bunker and to a police station, instructing her to tell police she was safe and in a relationship with him. The police officers, sensing something wasn’t right, took Eriksson into another room on her own. She then told them she had been kidnapped the week before and held against her will ever since, leading to Martin Trenneborg’s immediate arrest.

“He told me that the door was the same as they have in bank vaults, that the walls were made of thick concrete and that no one would hear me scream how much I tried and that it is impossible to get out from there.”

Trenneborg admitted holding Eriksson captive at his home, but he denied allegations of kidnapping and raping his victim while she was unconscious.

Two masks Trenneborg is believed to have worn as a disguise

Two masks Trenneborg is believed to have worn as a disguise.

During his trial, prosecutors told the court that documents had been found on his computer which amounted to sex slave contracts. Their contents suggested that he intended to hold his victim for 10 years and for her to agree to sexual acts on his request throughout her captivity. News.com Australia reported the contracts included clauses for ‘reductions in sentence’ in exchange for different sex acts and fines of ‘extra days’ for any refusal or escape attempts. Trenneborg was seeking a ‘girlfriend experience’ they reported. Furthermore, it is highly likely they said, that Trenneborg intended to kidnap more women to live inside the 60 square meter sized bunker.

His defense lawyer, Mari Schaub, told reporters outside the courtroom, “There is no simple explanations for this. This is a high-performing person who is unwell psychologically and has been longing for a life partner.”  Trenneborg, in his defense, claimed a mental disorder was the cause of actions, but it was not a claim well received by the judge.

Had Trenneborg’s crime not been discovered this could easily have been another terrifying case of a woman held captive for years in a secret sound-proof bunker no one knew about. Martin Trenneborg now joins names such as Joseph Fritzl, Cameron Hooker and John Jamelske in harrowing cases of abducted women and young girls held against their will before they eventually managed to escape.