A woman's badly burnt body is found in a remote spot, Ice Valley, near Bergen in Norway. Labels have been cut off her clothes and distinctive marks removed from her belongings. Police soon uncover coded messages, disguises, fake identities... That was in 1970 and the mystery was never solved. Last year we discovered further clues in the podcast, Death in Ice Valley. Now listeners have found more.
In the hills above Bergen surrounded by tall pine trees, large icicles hanging from the branches, we are back on the trail of the Isdal Woman. This is the cold and remote location at the centre of a mystery which has puzzled Norway for half a century.
There are so many strange details. Why was she here, seemingly alone, and unprepared for a freezing night in the wilderness? Why did she have multiple identities? Was she a spy? If so, who was she working for?
Her suitcases contained a coded note as well as disguises, and she swapped hotel rooms more than once. There was a mysterious meeting, it seems, with a naval officer. And why did the police shut down the case within just a few weeks, despite the many unanswered questions? Did someone want things hushed up?
Modern science has shed new light on this most cryptic unsolved case. Last year, we worked with forensic police to carry out isotope tests on her teeth and jawbone, the only parts of her body not buried after the case was closed in 1971. They connected the woman tentatively with Nuremberg in Germany. And the woman's likely age was revised - closer to 40 than 30.
Working together in the Death in Ice Valley Facebook group, listeners have also come up with theories about the Isdal Woman's mysterious travel itinerary - and identified the origins of a spoon found in her luggage.Join 21,000 amateur detectives on the Death in Ice Valley Facebook group Ten episodes of the podcast, first released in 2018, have been downloaded or streamed a total of five million times An 11th episode, recorded in Bergen last week,
We already knew many details from witnesses: she had a gap between her front teeth, ate porridge for breakfast and wore a fur hat. And she smelled quite strongly of garlic. We heard from people who, astonishingly, still remember meeting her, and noting her speaking in English with a "foreign" accent, five decades ago.
A black-and-white story from the last century has gained colour and context.
And now, new details.
"It's a good noise," Arne Magnus Vabo tells us, wielding his metal detector. The beeping is insistent and the quality of the sound tells him what kind of metal may be hidden underground.
Out on the same hillside, many months ago, the device alerted him to an intriguing find. The loud sound suggested a mixture of metals - maybe iron, maybe bronze or copper.
He dug down into the cold earth. Then he hit something.
Around 15cm (6in) beneath the surface he uncovered a handbag. The way it had been buried made him think it had been hidden deliberately.
"This was the first time I searched here," the 57-year-old says. "When you're alone, it's a creepy thing. You know people have used this place to have rituals or take their life. It's not a nice place to be." Vabo carefully removed the handbag, keeping it tightly closed, and let us know about the discovery. The Death in Ice Valley team then took it to the police.
The bag was heavy. Tree roots wound their way through its structure. It had been there for many decades.
Located just 40m from where the Isdal Woman's body was discovered, it appeared it could be the first new lead found in Ice Valley (Isdalen) in almost 50 years.
A few days later the bag was carefully opened in a forensic laboratory.
Nothing but soil was found. Any items once inside had been destroyed by time and the elements.
Experts cleaned it up carefully, revealing a blue-grey bag with red stripes. Short straps, about 35cm long, suggest it may have been bought for a child.
After so long in the earth, almost certainly dating back to the era of the Isdal Woman, experts said there was little point in testing the bag for DNA.
The excitement in the laboratory dissipated. The team had been hoping for remnants of a passport, identification of some sort, any clue to firmly connect the bag to the Isdal case. They did not find it.
"When I asked my father if he knew anything about my grandfather working on the Isdal case, my father had this reaction I'd never seen before. He got very quiet and it was like I punched him in the gut," says Cecilie Thorsted Flo. Even now, the memory of his reaction makes her emotional.
"The case broke my grandfather's trust in his work and my father said it was a case that had been very frustrating. My grandfather had this feeling that barriers were being put on their work," she says.
We know that Cecilie's grandfather worked in the Bergen Police and, although not central to the investigation himself, was close friends with one of the main investigators on the case. The pair often met to share their frustration.
Cecilie's father was just 10 at the time, but the memories have stuck with him. He will speak with us off the record, but otherwise he asks his granddaughter to tell this uncomfortable family story.
"I waited to write to you until I had heard eight episodes and then you started touching on the fact there were possible links to some foreign intelligence and possibly Israel," she explains.
"That was when I knew I had to write to you because the second after, my father said there was something about some links to Israel, and that was why the case was shut down.
"Once the police in Bergen had been working the case and digging deeper and found some connections to foreign intelligence, it seems like that was when the local police were shut down."
During the Death in Ice Valley investigation we found no strong indication of links between the Isdal Woman and Israel, although other researchers believe it is a plausible theory and we're still investigating.
Was the woman monitoring top secret trials of the Norwegian Penguin missile, which took place from the late 1960s? Classified documents, obtained by the podcast team, state that the secret police did investigate this possibility.
Other theories point towards possible spying for a non-government group, maybe one of the radical left-wing organisations that became notorious in the 1970s, such as the Baader-Meinhof gang.
Cecilie's sense, judging from her grandfather's strength of feeling, is that there is more to unlock.
"I understand my father and my grandfather a bit more after knowing about this. Both my father and I urge you to keep working this case."
Cecilie's words remind us that this mystery has affected many people and has not been forgotten despite the passage of so much time.
The crime club
Not far from Oslo, a group of young men meet around the dining table in one of their parents' homes. In front of them is a box and inside are some old newspapers and a large folder filled with police reports. They were friends already but now they meet up with a purpose: to try to solve the case of the Isdal Woman.
"We started listening to the podcast and came up with different theories about what happened," says Thomas Hayes. "We think she's a spy or something like that, because she was spotted by some military places in Bergen. I think she was tired of doing her job and killed herself."
But not everyone in the club agrees.
"I think she was a spy or an agent but how did she die? I think it was another man who killed her. I don't think she killed herself," says Fredrik Knudsen.
One day, club member Sindre Bratli showed up to a meeting with the box. It turned out that his uncle had looked into the case many years ago as a journalist.
"He was working for a newspaper in Bergen in the 1990s. Twenty-five years after the case he wrote a big article. He borrowed the documents from the police in Bergen and never delivered them back," Sindre says.
The documents in the box turned out to be copies of police documents. As with the bag, they are a tantalising but ultimately frustrating find.
Thomas Hayes is well-known because he stars in Norwegian online teen drama Skam, which follows the lives of a group of high school students and has been a hit not just in Scandinavia, but across the world. But while he has more than a million followers online, the Isdal Woman case has been something the four friends have so far kept to themselves.
"It will be interesting to tell people about it, when this [interview] comes out," he says.
"I have a lot of followers from Russia and Ukraine and they probably have relatives who have disappeared in the 1970s. Maybe something will come up. Maybe someone has a great-aunt or someone who has disappeared."
"I had to tell somebody about it, because this tragedy, it filled me up. I have remembered it for 48 years. I have always had a need to tell somebody. I didn't want to keep it to myself."
We travel on the funicular, a short rail line up the mountain in Bergen - it's 150 years old and very popular with tourists. We pass white, wooden houses, bridges and rock, and slowly the scenery becomes filled with snow and ice. We are here to meet Ketil Kversoy, a sea captain who used to live in the area. He has a story to tell.
At the top, Ketil walks us into the woods. The Isdal Valley is ahead of us, Bergen below. We're in deep snow here, it's winter, with hawthorn, spruce and conifer trees all around. It's very picturesque, with the occasional skier coming past but otherwise there's hardly anyone to be seen. It's very solitary. And Ketil hasn't been here for a long time.
"I have not been here since I had this meeting, 48 years ago. Before, I would go here quite often. But after that, I couldn't come here," he says.
He's talking about a day in 1970, when he believes he had a chance encounter with the Isdal Woman. It was late afternoon and he was on his way back to Bergen.
"I was surprised. Some people were coming up the mountain. That wasn't normal. I'd seen nobody else and I had been walking for a couple of hours," he says. A woman walked towards him, trailed by two men. All of them, he says were wearing clothes more suited to a visit to town, rather than the outdoors.
Their paths drew closer together.
"She was looking at me and her face, to me it looked like she was scared and she was giving up," he says. The men were about 20m behind.
"When she looked at me, I felt that she started to say something but she didn't and then she looked behind her and saw these men. I'm sure she knew they were going after her."
There are still elements of her appearance that he recalls to this day. "I remember her hair, dark hair, not too long. And also the men coming behind had dark hair. They didn't look Norwegian, I was thinking southern Europe."
Although he would eventually tell the police what he had seen, he regrets not speaking up sooner. "I waited too long. I didn't go to the police station because I felt like a crazy man coming and telling a crazy story."
But a friend of his who was a police officer at the time told him that the case was beyond the Bergen force. It was an international case, he said, and it would never be solved.
Ketil says his meeting with the woman happened on a Sunday, late afternoon, and that is the awkward thing about this story.
The Isdal Woman was found on a Sunday morning and the last sighting of her is on the Monday, almost a week before she was found. This encounter, if it was with the Isdal Woman, can't have taken place on the Sunday she was found, so it must have been the Sunday before, or another Sunday. But that doesn't mean it wasn't her.
Listeners have asked why we haven't compared the DNA profile of the Isdal Woman with the biggest commercial databases, which contain millions of DNA profiles.
The DNA material in the case belongs to the Norwegian police and, for legal and ethical reasons, they have so far not allowed the material to be run through commercial databases used by people to find out about their ancestry.
But there might be hope for the future.
The use of genetic genealogy to solve identity cases has been experiencing explosive growth, especially in the US. This is where an unknown person's DNA is used to track down distant relatives. This information is combined with traditional genealogical methods to build family trees that help uncover the unknown person's identity.
Joseph James DeAngelo, a former police officer, was charged with eight counts of first degree murder in April 2018, based on DNA evidence gathered in an investigation to find the so-called Golden State Killer.
In another American case, known as the Bear Brook Murders, the identities of three murdered people have been confirmed by police. Marlyse Elizabeth Honeychurch and her two daughters, Marie Elizabeth Vaughn and Sarah Lynn McWaters went missing in the late 1970s. Genetic genealogy also helped to identify the man most likely to have murdered them - Terry Peder Rasmussen, a serial killer who died in 2010. A fourth victim, thought to be a female child, has yet to be identified.
The story has been made famous around the world in the NHPR podcast, Bear Brook which shone a light on the work of amateur genetic genealogist Barbara Rae-Venter. Her research linked various crimes attributed to Rasmussen.
Coleen Fitzpatrick, a leading expert in this area of DNA research, has contacted the Death in Ice Valley team, offering to help identify the Isdal Woman.
"I read an article on how you had already done some isotope testing which narrowed down her origins, so that piqued my interest," she says.
She's part of the DNA Doe project, a volunteer-run organisation that uses genetic genealogy to identify unknown people ("John and Jane Does", as they are known in the US).
"We handle many cases that have had the isotope testing done and we've actually identified those people," she says. "The Isdal Woman is a very well-known case and it's very interesting, we'd love to work on it."
The wheels are slowly in motion in Norway now.
It's been recognised these methods have launched a revolution in the solution of cold cases, so there will now be a legal hearing to decide if the police can do the same with the Isdal Woman.
It's not clear when that hearing will take place. But for the time being, we wait and hope.
Live in Bergen
Three of the key players in the Death in Ice Valley podcast join us on stage in a darkened room, in the University of Bergen students' union.
In front of an audience of the podcast's fans - many from Bergen, but some from places such as Germany, France and Iceland - we talk through the investigation with forensic pathologist Inge Morild, crime writer Gunnar Staalesen and Nils Jarle Gjovag from the Bergen Police.
"My personal theory," says Staalesen, "is that she was hunting for Nazi war criminals… Israel and Norway had a very friendly connection, so if the secret services knew that was what she was doing here, they would keep that a secret. But it's only a theory."
Some of the audience wonder if she could have died somewhere else and then been taken to the location where her body was found. But Morild thinks this unlikely.
"She was breathing in smoke and there was a fire [by her body] so she must have died on the spot where the fire was," he says. "Or there has to have been smoke or fire some other place, which, to my knowledge, wasn't reported. I think she died at the place where the fire was."
Discussions like these, and the level of interest in the case, are reassuring to senior police officer Nils Jarle Gjovag.
"In many cases, especially cases like this, we're depending on the people out there," he says. "The people are the greatest detectives. In this case, we are trying to get the identity of an unknown woman and we don't know where she came from. To get the case out in the world like this, perhaps somebody out there will say something like, 'Hey, I had an aunt who went missing at that time - could it be her?'"
Since launching the Death in Ice Valley podcast, we've been getting information from people across the world. Maria, a student in Bergen, wants to know how we decide which leads to investigate.
The answer is that a joint team at NRK, the Norwegian national broadcaster, and at the BBC World Service in London, sifts through the leads, and recommends new ideas - ones we haven't seen before - for further discussion. Some of them we can't resist but follow up, though they don't always lead anywhere.
Ian Briggs, in the Facebook group, asks if we're making more episodes of the podcast.
It's too early to give a definite answer, but some of the new leads are taking us to places we truly didn't expect.
Readers who want to share tips about the case of the Isdal Woman can
Additional reporting by Amelia Butterly and Anna Doble