In the early hours of Wednesday 6 February 1985, Odd Petter Magnussen drove through a police roadblock in his haste to get to the local hospital. His wife, Kristin, was in labour and the contractions were coming so rapidly that Odd Petter was anxious she might give birth in the car. He pressed down on the accelerator, ignoring the speed limit. There had been an accident on the motorway leading into Oslo but, when the police tried to flag him down, Odd Petter was having none of it. "I just drove completely through the roadblock," he recalls. "I went through the red lights, everything, until we got to the hospital."

Within three minutes of arriving there, the baby was born. They called her Martine. Their first child, Magnus, born a year earlier, had been a fortnight overdue. By contrast, Martine seemed determined not to hang about. "Her mother has said that Martine came into this world very speedily, very early," says Mr Magnussen, "and she left very early as well." His voice trails off.

Martine Vik Magnussen's life was cut short without warning. Twenty-three years after that morning dash to the hospital, Mr Magnussen had to identify his daughter's body in a police mortuary. She had been living in London when she was killed: the last time anyone saw her alive was when Martine left Maddox, an exclusive nightclub off New Bond Street, between 2am and 3am on the morning of 14 March 2008. She got into a taxi with her friend and fellow student, Farouk Abdulhak, the 21-year-old son of one of the most powerful men in Yemen. Martine was never seen alive again.

Two days after Martine went missing, police discovered her body in a state of undress, dumped in the basement of a block of flats at 222 Great Portland Street, where Abdulhak had been living. A token attempt had been made to disguise her body with bits of rubble. Items of her clothing were missing: snakeskin shoes, a Marc Jacobs handbag, a Guess watch and one of a pair of Christian Dior earrings. Abdulhak was nowhere to be found. The following day, his friends noticed that he had erased his Facebook profile. Later, it would emerge he had boarded a scheduled flight from Heathrow to Cairo on the afternoon of 14 March. From Egypt, it is believed he fled to Yemen on his father's private jet.

The police officers had already tried to prepare Mr Magnussen for the sight of his daughter's body by telling him the worst. They told him that they suspected Martine had been raped and strangled. They warned him he might notice bruising on her face – the discolouration of her skin across the bridge of her nose a testament to the fact that she had fought hard for her life. They told him all of this and yet nothing, in the end, could prepare him for the sheer force of emotional pain that hit him in the pit of the stomach when he saw his beloved daughter lying cold and lifeless in front of him.

Mr Magnussen tries now to put the experience into words as he sits on a beige armchair in the front room of the home where Martine grew up. The house is a squat wooden structure, built into the edge of a hill on the small, picturesque island of Nesoya, a 15-minute drive southeast of Oslo. To Mr Magnussen's left, a broad sweep of window overlooks the snow falling silently into the fjord below, the frozen waters stretching out into an infinite expanse of whiteness dotted by the dark silhouettes of pine trees.

"She still had eyeshadow on," he says after a while, in excellent English. "She still looked very much like herself. I touched her face." He stands up from his chair and walks over to me. "Like this." Gently, he strokes my cheek with the flat of his bent fingers. Before he can stop himself, he is crying, the tears appearing in a sudden flurry. With one hand raised to his mouth, he tries to suppress the half-muffled sobs. For a few seconds he is unable to continue and then, briskly, he wipes his tears away with a paper tissue and apologises. "I get these reality checks from time to time. They come and then they're gone. I don't normally cry very easily." He tries to smile, but the effort it costs him is more upsetting to watch than the tears, because what makes Mr Magnussen's grief incalculably worse is the knowledge that his daughter's killer remains at large.

Next month will mark the two-year anniversary of Martine's death and the prime suspect is believed still to be in Yemen, sheltered from justice by his powerful family and profiting from a legal loophole that means his native country has no extradition treaty with Britain. "This is the oldest and most serious crime known to man: the raping and killing of a woman – in any culture, in any religion, in any nation of the world," says Mr Magnussen. "Why should this family be beyond the law?"

Martine Vik Magnussen had moved to London in February 2007, filled with excitement about what her new life in the city would hold. After leaving school in 2004, she worked for a while in various clothing shops near her home, including the Oslo branch of Massimo Dutti. Two years later, she went to Warsaw to study medicine, but she found it difficult to settle in, and quit her studies after six months.

On her return to Norway, she told her father she wanted a change in direction. Many of her friends had already moved to London to study and Martine looked into the possibility of doing a business degree there. Her father, who had spent time as a student at Herriot-Watt University in Edinburgh, was supportive and eventually she enrolled at the Regent's Business School in Regent's Park, London, a rapidly expanding private college with a multicultural student body. She moved to London in February 2007 and chose to study International Business Relations when term started in September. Among her classmates would be Farouk Abdulhak.

When her friends and family describe their memories of Martine, the word that comes up most often is laughter. Her father recalls that she could make him "double over" merely by altering her facial expression or by walking into the room in a particularly clownish fashion. She was always the most extrovert of his three children – Magnus, 26, and Mathilde, 20, were quieter, more academic. They were a close, loving family – although Martine's parents had divorced amicably in 2000, they continued to spend Christmases and birthdays together. Magnus and Mathilde have been so numbed by her death that neither they, nor their mother, want to speak publicly about what happened.

"If you could have seen what Martine meant to them and how extremely close these children were, what they have lost is beyond comprehension," says Mr Magnussen. "She was a light, jolly, enjoyable person. In any social setting, she could lift any sort of atmosphere. She was pure sunshine."

One of Martine's best friends, Hedda Homme, who knew her from the age of 16, says that she was "so funny all the time. She always made people laugh. She was so happy. Everyone liked her. She was always letting me know what she thought. She was honest, you could trust her."

Every summer in Norway, Martine would throw a party in the beach hut at her family home in Nesøya. In London, she liked to host dinner parties, cooking recipes that her mother had taught her (among her friends, her chocolate brownie cake was the stuff of legend). Sociable, popular and kind, Martine loved meeting people from different backgrounds. She became part of a fun-loving, international crowd who made the most of the cosmopolitan nightlife on offer.

After her murder in 2008, the tabloid press were swift to label Martine as a "party girl" whose favourite haunts were the exclusive London nightclubs that specialised in attracting a hip and glamorous European clientele. At Maddox, which operates a strict members-only door policy, a bottle of vodka can cost £800. But although Martine's family were comfortably off – her father is a marketing manager specialising in IT – and, like most students in their early 20s, she enjoyed a night out, her friends make it clear that she was also street-smart and responsible with money. She took part-time jobs to support herself, including one stint as a shop assistant at the Mulberry clothing store in Mayfair. She was careful, too, about going out at night.

"In London, our friends were our family," says Martine's former flatmate, Thale Lassen. "We had rules: if you don't come home, always text, always stay in touch. Martine had an ability to make everyone feel special," she says. "Within 10 minutes of meeting someone, she knew what their favourite food was and the name of their dog if they had one. She'd mesmerise people around her. She stood out in a crowd. In Norwegian we have this term that means almost like an inner light that shines out from you. That's what she had."

She was beautiful, too, with her blonde hair and hazel-green eyes and her slim, 5ft 4in frame. She was popular with boys, but never had a serious boyfriend. When she moved into a modest flat on the Chelsea Bridge Road in June 2007 with three Norwegian friends – two girls, including Lassen, and one boy – her female flatmates would joke that there were no men left in London for them, because they all had a crush on Martine.

At first, Farouk Abdulhak seemed to be just another of Martine's many admirers. "She saw Farouk all the time," recalls Lassen. "They were good friends. She talked to him on MSN and on her BlackBerry. She made me add him as a friend on Facebook. She would say, 'He's such a nice guy, he's so funny.'" Lassen met him once, when he came round to the flat to pick Martine up. "He didn't seem like a bad guy," she admits. "I only met him for about 10 minutes. He was a bit shy and Martine did most of the talking. We teased her because they were spending a lot of time together: we would say, 'He has such a crush on you!' but she would always deny it." According to Lassen, Martine and Farouk were never romantically involved.

At the Regent's Business School, classmates remember Abdulhak as a shy and friendly presence. "He was supposed to be very nice, actually," says Mr Magnussen. "Some of his friends have said he wouldn't hurt a fly. If he scratched another person's car, he'd leave his name."

Much of his background is sketchy, but the police were able to establish that Farouk Abdulhak was born in Yemen, the son of a billionaire, Shaher Abdulhak, an extremely powerful figure in Yemeni society and a man whose business empire extends into petroleum, sugar, soft drinks, tourism and property. Notoriously publicity-shy, Shaher Abdulhak has never granted a single interview and no photograph has ever been printed of him in the local press.

Farouk attended the Azal Hadda primary school in Yemen before being sent to boarding schools in Britain. He also spent time in the US and is believed to hold an American passport. In London, he rented a £600-a-week flat in Seaford Court on Great Portland Street, and although he came from a strict Islamic background, he drank, smoked and described himself as "agnostic". There were rumours that Farouk's father had urged him to cut back on his partying in order to be groomed to take over the family business. At the time of Martine's death, a friend was quoted as saying that Abdulhak "was under a lot of pressure to uphold his family's honour".

On the night of Thursday 13 March 2008, Abdulhak was one of a group of students from the Regent's Business School who went out to Maddox to mark the end of term. Martine, who went to the club with her flatmate Nina and some other friends, had more reason than most to celebrate: she had come top of the class in her exams.

There is a photograph of Martine and Abdulhak from that night, taken in the midst of an anonymous bustle of clubbers, the two of them picked out by the camera flash in a circle of bright light (the image on the cover of this magazine). Martine is leaning into her friend, one arm around his back, and is smiling, perhaps a little uncertainly. Abdulhak is staring intently at the camera, his mouth set in a straight line, his hand clenched tightly around the neck of a beer bottle. "He has terrifying eyes in this picture," says Sophie Terkelsen, a friend of Martine's from secondary school. "It's like he's angry about something."

At around 2am, Martine's friends decided they wanted to go home. Martine had heard of another party in a different part of town, so she got in a taxi with Farouk. A week earlier, Martine had lost her mobile phone, so when her flatmates noticed on Friday morning that she was not in her bedroom, they tried to contact both her and Farouk through Facebook.

"At first, I was a bit angry and upset because she knew the rules [about getting in touch]," says Lassen. "We went back to Maddox that evening, we were sending her Facebook messages saying 'Contact us, call us, we're here, come and meet us, let us know you're all right.' At midnight, we started to feel really anxious." Lassen and Nina returned to the flat. "I was like 'OK, be in your bed sleeping, make fun of us for worrying,'" Lassen says. "She wasn't there. And that's when we freaked out."

At the same time, they noticed something suspicious about Farouk's Facebook page. There was a status update made at around 4am that read "Farouk is home alone" even though they knew that Martine had left Maddox with him. Martine's flatmates called everyone they could think of who might know of her whereabouts and set up a Facebook group appealing for information. They retraced her steps and handed out flyers with her photograph. No one knew where their friend was.

On Saturday, they reported Martine's disappearance to the police. "Their first reaction was: 'Oh, she's a 20-something girl student in London. She's out partying,'" says Lassen. "We spent the next 24 hours pushing them to go to Farouk's apartment." By Saturday evening, Abdulhak had erased his Facebook profile. His friends said he had been called back to attend to urgent family business. Later that night, Lassen called Martine's parents to let them know their daughter was missing.

Mr Magnussen remembers the phone ringing at about 11pm on the day before Easter Sunday. "After 10 or 15 minutes of conversation and listening to everything they had done, I said to them, 'I think we have a situation where we will never see Martine alive again.'" He says he knew instinctively that Martine was dead.

The following day, the Magnussens flew to London. They were picked up from the airport by officers from Scotland Yard and taken to Belgravia police station. "After half an hour, some police officers came in," recalls Mr Magnussen. "They said: 'We have reason to believe we have found your daughter in the basement of this building. She's dead.' The rest of the family broke down. For me, that was a slight relief. Do you know why? Because there is one thing that would have been worse and that was that we'd never find Martine, that they'd managed to get rid of her body, that we would never have a grave to visit or be able to find out what happened to her."

In a nearby room in the same police station, Martine's flatmates had gathered to be told the shocking news. "It was horrible," says Lassen. "I don't remember the next hour or so. We broke down completely. We all left London the next morning. We took the first flight out."

Later that same day, the Magnussens were taken to the Grosvenor House Hotel in Mayfair. They stayed together, in a family room, under a pseudonym provided by the police to fend off the journalists who had already begun to gather outside. "We said to each other, 'Don't hold back any emotions, get it out, don't be afraid,'" says Mr Magnussen. "During the next 24 hours, Mathilde [then 18], Magnus [then 24], my ex-wife and myself burst into tears and cried completely independently and spontaneously throughout the night. I think it was very good to have that."

On Tuesday, the Magnussens went to identify Martine's body. The cause of death was established as compression to the neck causing strangulation. Two weeks later, Martine's body was flown home to Oslo to be buried in Asker churchyard near her home. At her funeral, her brother Magnus took to the pulpit and thanked his sister for "the time with blue sky".

Back in London, it soon became apparent to Detective Chief Inspector Jessica Wadsworth that all the evidence pointed in one direction. "Very quickly, we knew who we wanted to speak to," she says, sitting in her small, grey-carpeted office in the Homicide & Serious Crime Command unit of the Metropolitan Police in Hendon. In the days after the discovery of Martine's body, an appeal was issued for Abdulhak to come forward with any information relevant to Martine's death. There was no response. In Yemen, the local newspaper printed a statement issued by Abdulhak's uncle through a third party which said they would not associate themselves "with any member of the family connected with any wrongdoing".

The legal situation was complicated by the fact that Yemen has no extradition treaty with the UK and that it would require diplomatic co-operation for officers from Scotland Yard to travel there. The British authorities could not agree to a trial for Abdulhak in the country of his birth on ethical grounds in case he faced the death penalty, and yet there was no way of forcing him to return to the UK without the agreement of the Yemeni government. In a deeply conservative country, where justice is considered a family affair rather than a matter for the state, the fugitive Abdulhak could quite easily be sheltered for months, even years, by a father with extensive financial resources and powerful political connections.

In the first few days of the inquiry, codenamed Operation Debruce, DCI Wadsworth managed to speak to Abdulhak's father, Shaher, over the telephone. "He, at that time, claimed he had no knowledge of his son's whereabouts," she says. "He said he would contact his lawyers and they would get in touch and that's the last communication we had with him."

Instead of co-operating further, Shaher Abdulhak consulted London-based law firm Peter & Peters, experts in extradition law. He then employed David Wilson, the managing director of the public relations firm Bell Pottinger, to act as his spokesman in the UK (an attempt to communicate with the Abdulhak family through Mr Wilson for this article was met with silence). On Thursday 20 March, a week after Martine's disappearance, Shaher Abdulhak met Yemen's interior minister, Rashad al-Alimi, apparently seeking guarantees his son would not be handed over to the UK. Despite the evidence gathered by her team, DCI Wadsworth's hands were tied.

Rumours of Abdulhak's whereabouts have sporadically filtered back from Yemen since his disappearance: at first, he was believed to have been taken to a family property in a village four hours outside the capital Sana'a, in the al-Arooq district of the Taiz region. Then, he was believed to have been moved to a succession of his father's hotels and retreats in the countryside. He is said to have grown a beard in order to fit in more seamlessly with the strict Islamic culture. When a Norwegian documentary crew travelled to Yemen in summer 2009, they filmed the Abdulhak family lawyer on a hidden camera, admitting that Farouk lives at home with his family and studies Arabic at the local university.

In July 2009, the police passed their investigation on to the Crown Prosecution Service, which decided there was sufficient evidence to prosecute Farouk Abdulhak for Martine's murder. He was placed on Scotland Yard's "Most Wanted" list and a European arrest warrant was issued. But now that the police investigation has been completed, the process of bringing Abdulhak to trial is a largely political matter, dependent on the diplomatic oiling of cogs and wheels behind the scenes by the foreign secretary, David Miliband, and his Norwegian counterpart, Jonas Gahr Støre.

And yet, almost two years on, Martine's murder is still unsolved, raising the horrifying spectre of something similar happening again. "It's just that awful feeling that injustice prevails," says DCI Wadsworth. "We will pursue and pursue and pursue… I understand that he [Abdulhak] continues to protest his innocence; well, if you're innocent, then come back, you've nothing to fear." Wadsworth says that she still nurtures "an outside hope" that Abdulhak's family will hand him over, or that he will tire of the restrictive Islamic lifestyle and start hankering after more western pleasures – parties, drink, girls – that are only available outside Yemen.

For Mr Magnussen, the process has been slow and frustrating. Although he has nothing but praise for Scotland Yard and the British authorities, he remains extremely disappointed that his own government has not done more to put pressure on Yemen.

"This is not only a question of a lack of extradition treaties," says Mr Magnussen, who is determined that Abdulhak should face trial in the UK, where the crime took place. "It's a simple matter of right and wrong. This has to do with a moral obligation. People are dying every day throughout the world, but what makes this tragedy challenging to us is that this is not a natural catastrophe.

"The particular tragedy in this case comes from the worst motivation a human can have: to kill a person, to put yourself as a judge over their life, to take that life away because it suits you. That is beyond excuse, that is beyond comprehension." He breaks off, gathering his thoughts. "And he [Farouk] can just lie by the pool down in Yemen and live happily ever after. What sort of a father would I be if I didn't do everything I could to prevent this happening to other children?"

Is he angry? There is a long pause. He is a dignified man, not much given to displays of excess emotion. "Of course I am, and I'm disappointed," he says, finally. "I'm trying not to use up any effort in hating. I'm trying to see justice prevail here for the benefit of Martine." Most of his days are now spent finding new ways of putting pressure on the Norwegian government and the international community to raise the profile of the case. When I ask whether burying himself in this sort of work acts as a form of therapy, he interjects before I can finish the question. "No," he says, blankly. "If I needed positive therapy, I would not be digging in this cellar of disappointment. Everything has been a setback."

What makes it particularly hard for Mr Magnussen to come to terms with his daughter's death is not only the knowledge that the chief suspect in her murder is still at large but that, if Farouk is indeed the killer, there was nothing obvious Martine could have done to protect herself: he was a good friend, a man she trusted and had known for several months. She did not leave the club that night with a stranger, nor did she act wilfully, or take a stupid risk. Her only fault was perhaps to trust too easily, to think too well of others and to imagine that the friends she made would, like her, possess a strong moral code. For DCI Wadsworth, "This was a case where it seems as if there's nothing she could have done differently. It's just not fair. They were good friends and obviously, that night, only the two of them will ever really know what happened." Thale Lassen puts it more bluntly: "It really doesn't make sense. Would you ever suspect a good mate of raping and killing you? It's just crazy."

In the margins, there are nonetheless signs of quiet progress. The Yemeni government is under increasing pressure to co-operate more closely with the international community after it emerged that Umar Farouk Abdulmutallab, the alleged Christmas Day bomber, was radicalised by al-Qaida operatives in Yemen. According to Arne Elias Corneliussen, the Magnussen family spokesman: "It would increase the legitimacy of the [Yemeni] regime if Mr Abdulhak is extradited, as it would be seen as an important step in the direction to remove corruption and to abide by international standards and norms in the face of serious crimes."

In Norway, Martine's friends and family remain determined that her death should not be sidelined. Before Christmas, her childhood friends, Sophie Terkelsen and Hedda Homme, organised a 1,000-strong torchlight procession to highlight awareness of the case. Earlier this month, they launched a new campaign website, justiceformartine.com, and on 10 February Mr Magnussen attended a pre-inquest review in London and met Chris Bryant, the parliamentary under-secretary of state for the Foreign Office, to discuss the possibility of securing a one-off legal agreement to secure Abdulhak's return.

"This murder concerns Martine, but it also concerns the international community because this could happen again," says Terkelsen. "When you can go to your native country and stay there in a safe haven, you know that's a big international safety problem." Homme nods her head in agreement. "We don't want revenge, we just want justice," she adds. "Justice for Martine."

It would have been Martine's 25th birthday this month. On Saturday 6 February her family visited her grave – a quiet, sombre group of four, where once they would have been five. Beyond that, they did not want to mark the day. Their grief is still so immeasurable that sometimes they fear it will engulf them . "It is a survival thing," says Mr Magnussen. "We cannot take it in or think about the consequences on a daily basis, because it will destroy us. When you see me cry, as you have done today, that is barely touching on the scope of this tragedy. In our family, this loss is so big that we try to minimise talking about it."

Before I leave, Mr Magnussen insists on showing me the beach hut at the bottom of the steep-sloped garden. It is a tiny wooden cabin, complete with a small sauna and a terrace built along the frozen shoreline of the sea. It was here that Martine invited her friends each summer for a party when the sounds of high-spirited teenagers laughing and drinking and jumping into the clear water would last late into the evening.

Today, the ground is several inches thick with snow. Mr Magnussen looks around, as if testing the air, and then he walks to the edge of a long jetty, his footsteps making hollow marks on the unbroken snow. He stands there for several minutes, a grey figure looking out across the immeasurable whiteness of sky and sea. For a moment, he seems vulnerable: slight and fragile against the uncompromising enormity of the landscape. But then he turns and walks back to the shore, towards the beach hut that his daughter once loved, letting the vastness recede behind him.