‘My date drugged me, kidnapped me and kept me trapped in an underground bunker’

For years, Isabel Eriksson, 39, couldn’t own a fridge. She was terrified of them. The buzzing and humming they made as they clicked on and off caused panic attacks and she would avoid them in other people’s homes. Living in the cool climate of Sweden, she kept her food outside instead.

That’s because the noise of a fridge transported her back to the bunker, a terrifying, windowless room she’d been drugged, taken to and kept in against her will by a man she’d trusted.

‘Who knew that a person could have so much darkness in them?’ Isabel tells Metro over Zoom from a secret location. Understandably, the 39-year-old Swedish national, who speaks under a pseudonym, doesn’t like to give out details about her life.

 ‘I didn’t know him that well, but he was someone I trusted. He was a doctor. No one ever thought he could do anything like that.’

Isabel had asked Dr Martin Trenneborg to her apartment on a date in September 2015. Recalling that evening, she says: ‘He came in with presents; a bottle of perfume and small white and pink flowers. He said he picked them himself, which I thought was sweet. It all felt pretty good and he seemed quite normal. But there was one thing I noticed – he had a very intense gaze, in a way I haven’t felt before.

‘Psychopath eyes, is the description that came to mind, but I pushed that feeling away as I thought he was otherwise nice.’

However, Trenneborg was anything but nice and the doctor has since been dubbed the ‘Swedish Fritzl’, after the case of Austrian Josef Fritzl, who kept his daughter locked up in a cellar for 24 years. Unbeknown to Isabel, some of the chocolate covered strawberries he’d brought for them to share had been laced with rohypnol. He had secretly marked the ones that were drug free so he knew which ones to eat. 

Isabel soon felt dizzy and passed out. When she woke, she was 350 miles away from her home, but had no idea where she was.

She is now sharing her ordeal in The Bunker, a new Amazon Prime documentary. Recalling the moment she came round to the camera, Isabel says: ‘I’m dazed. My mouth is dry, and I slowly open my eyes. I look straight up at the ceiling. It smells bad. I don’t know what day it is or what time of day. I realise I don’t know where I am. I’m lying under a blanket wearing a pair of jeans and a pink jumper. My body feels slow and it aches. When I turn over. I couldn’t feel any underwear under my jeans. It’s cold…’

Isabel also felt a burning in her arm. When she looked down she saw a cannula. As she ripped it out, a voice said: ‘It would have been better if I’d taken that out. I am a doctor, after all.’ Trenneborg was also in the room, sitting in a chair, watching her.

Isabel passed out again and as she regained consciousness, her toy poodle Nellie was next to her, licking her face. She tried to work out where she was and how she’d got there. On a bed in a newly constructed room with a fridge, Isabel noted a kitchen bench, a couple of chairs, bare plaster walls and no windows. It was dirty and dusty and strip lights buzzed above her. It smelled stagnant.

The place was silent too, she realised: no sounds of nature or human life. All she could hear was the humming of the refrigerator, clicking on and off at intervals.

Trenneborg came into the room, passing through three heavy doors that were secured with keys and code locks. Isabel tried to attack him and make her escape but he overpowered her easily and warned her not to do it again. Later, he bought a sandwich and told her he would paint the walls of the bunker to her liking. Isabel, terrified, tried to be compliant.

‘He gave me three books to read; they were about women who had been raped and murdered,’ she tells the documentary. ‘I didn’t know how to interpret it. He shows me a room in the bunker, he said it would be a torture chamber. I didn’t know if he would build a real torture chamber, like he said, or if it was just some kind of sick game to really scare me.’

Isabel was terrified. Trenneborg took swabs and vaginal tests, telling her it’s so they can have unprotected sex. He would come and go with Isabel having no idea of whether it was day or night or how many hours or days had passed. While he was at work at a nearby medical centre, she spent her time pacing the room, doing sit ups and push ups, trying to keep her body and mind strong to work on her escape, while calming herself down by looking after Nellie.

On one occasion, Trenneborg took her, shackled, to his house to shower, and allowed her into a tiny exercise courtyard. It was then she realised he’d constructed the tiny jail next to his home in a secluded wooded area. As he led her back to the bunker her heart sank; the entrance looked like the ‘gates to hell’, she remembers.

He told Isabel that he would keep her for ‘a couple of years’. ‘I don’t know what he has planned for me after that. To murder me and bury me in the woods,’ she remembers.

Back in Stockholm, when her friend couldn’t get hold of her, she contacted Isabel’s mother who told the police. They visited her home, taped it off and locked it and launched a missing person’s enquiry.

By the fourth day of her incarceration, Trenneborg had Isabel cooking for him, and they sat together as he discussed his day, mimicking a normal relationship. She complied, trying to keep him on side to stay safe while she desperately planned her escape.

Then, on the fifth day Trenneborg came in with a gun in his hand.

‘At first, I think he’s going to shoot me. Maybe someone has found him out. But instead he says he’s had it in his mouth, but not dared to pull the trigger. He gives me the gun, forces it into my hands. I’ve never held a gun before. He says, the doors are unlocked. I just have to shoot then I’m free,’ she tells the documentary. 

Isabel wondered if it was a trick. If she was left with his body and unable to get out, she would die behind those reinforced concrete walls.

‘He was the only one who knew I was there. Nobody would find me. It was horrible. I’m freaking out. my hands just shake, even if it’s my way out, I don’t dare. I cry. I give him back the gun,’ she explains.

The following day, Trenneborg returned as if nothing had happened, and told Isabel she’d fallen in love with him. She went along with the charade and said she needed clothes from her apartment. Miraculously, her captor agreed.

They made the long journey from Kristianstad in southern Sweden to Stockholm, but on their arrival, found it locked and bound with police tape. Trenneborg brazenly took Isabel to the local police station where they pretended she had been visiting a friend for a few days and was annoyed to find her home under investigation. Her luck changed when a police officer took her into an interrogation room and she desperately explained what had happened.

Four officers went back out into the foyer and arrested Trenneborg. Isabel was free.

The police investigation revealed how meticulously he had planned the kidnap; he’d packed nappies and a wheelchair on the date, so he could transport Isabel cleanly to his home while unconscious and had placed a line in her vein so he could administer further drugs. The bunker was secure; one door had five locks, it was soundproof and he’d ensured there was enough ventilation to house seven people. Building it would have taken years; he called it his ‘master plan’.

Trenneborg later told police he’d struggled romantically and that he had kidnapped Isabel to keep her as his girlfriend. He’d told Isabel he was going to bring other women there.

Looking back over her experience, Isabel, who was a sex worker at the time, says she regrets letting Martin into her home for a paid date. She was dogged by trauma after the harrowing experience. 

‘My fears are panic, fear of death, hopelessness, I feel isolated. My life has shrunk. I can’t do what other people do,’ she says, resigned. Heartbreakingly, her dog Nellie died soon after the kidnap. ‘She was so bouncy and happy before but she developed certain behaviours after the time in the bunker,’ Isabel explains. ‘It’s sad; she became aggressive and barked and growled at people who came near me.’ 

For years Isabel remained in the bunker emotionally. She had to take sleeping pills, and would wake in the night, not knowing if she was still incarcerated.

‘In the beginning I was so easily frightened. I didn’t like closed doors. I had to have a light on all the time when I was sleeping, and I would fear thunderstorms,’ she says. ‘I felt like it was maybe him, closing the doors. I would wake, screaming, panicking.’

Suffering from PTSD, Isabel says she was constantly on edge, suffering from nightmares, terrifying memories and panic attacks. The noise of the fridge would cause flashbacks.

The trauma changed who she was as a person. She’d had a happy childhood, at home in nature and riding horses. But after the kidnapping she was withdrawn, isolated and seriously struggling with her mental health. She dissociated from reality and struggled to trust people.

Today, Isabel lives under a different name in an unidentified location. Trenneborg was jailed for ten years in 2016 but Isabel received a letter explaining that her captor had been released in August 2023.

‘I had no idea where he’d go or if he’d want to get revenge on me. I felt very scared,’ she says. ‘It’s been hard to go through, and some things are still hard. The kidnapping will always be with me, but it’s something I have to learn to live with. I’m not going to let it stop me.’ 

Medication and therapy have helped Isabel, along with time. She is now planning for her future and is starting an exciting new career as a dating coach. Being with friends helps too, and walking in nature. And she owns a fridge again.

Making the documentary also helped her recover, Isabel adds, as it forced her to safely process her memories. ‘It’s like a journey,’ she explains. ‘Perhaps one that is going on for a long time. But I am doing okay now.’

–   The Bunker is available to stream now on Viaplay via Amazon Prime Video

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