Natascha Kampusch (pictured) was kidnapped when she was 10 years old on March 23, 1998. She was not seen again until August 2006

On a hot summer day in a small Austrian town, a very agitated young woman ran up to an elderly man out walking with two friends. Breathing heavily and repeatedly looking over her shoulder, she babbled that she had been kidnapped.

As the startled companions explained that they had no mobile phone to call for help, the girl darted off. She ran through gardens and climbed over fences. She banged at one door, begging to be let in, but there was no answer.

After running across the garden to a neighbouring house, she knocked and the door swung open. Her ordeal was over. The woman who answered listened to the girl's breathless tale, ushered her in and called the police.

The desperate young woman's name was Natascha Kampusch, and she had disappeared eight years earlier as she walked to primary school from her home in Vienna, half an hour's drive away. Witnesses had seen a man push the ten-year-old into a white van just before 8am on March 23, 1998. Then she simply vanished.

She was not seen again until that August day in 2006, when she told astonished detectives she had been imprisoned in a cellar under a garage for eight years, where she was beaten, raped and treated like a slave.

Her kidnapper was Wolfgang Priklopil, 44, a computer technician and property developer, who liked her to call him 'Master' and held her until she finally escaped at the age of 18, when her jailer was distracted by a phone call and she ran for her life.

But while the world's media was transfixed by the story and Natascha went on to make millions from book and film deals, her kidnapper took his secrets to the grave.

For within hours of Natascha escaping, he was found beheaded by an express train, after apparently lying down on railway tracks and taking his own life rather than face justice.

In what was explained at the time as Stockholm Syndrome, the psychological phenomenon whereby hostages become attached to their captors, Natascha sobbed when she was told about Priklopil's death.

Even more bizarrely, in the hours after her escape, she asked police if she could be taken to the mortuary where her captor's remains were awaiting forensic tests and eventual burial.

To the astonishment of the officers, she threw herself over his body and wept.

Natascha's kidnapper was Wolfgang Priklopil, 44, (pictured) who liked her to call him 'Master' and held her until she finally escaped at the age of 18, when her jailer was distracted by a phone call and she ran for her life

Now, a decade later, the life of Natascha Kampusch is once more under intense scrutiny.

The story of the 28-year-old, who always carries a photograph of her kidnapper in her handbag, is at the centre of a saga involving allegations of a high-powered child sex ring, police corruption and murder.

Indeed, the claims concerning Natascha's abduction, nearly 20 years after she went missing, are as disturbing as the fact that a young child could simply disappear for eight years.

They centre on sensational claims that Priklopil, known as 'Wolfi', was murdered before his body was placed on the tracks between the Praterstern and Traisengasse stations in Vienna.

Der Spiegel, the respected German news magazine, has revealed that two eminent coroners investigating the case believe Priklopil's death was 'not investigated to acceptable forensic standards' by police and that he may have been killed before the train decapitated him.

In a damning judgment, the coroners, Johann Missliwetz and Martin Grassberger, declared that medical and legal reports concluding that Priklopil's death was suicide were 'worthless'.

To add weight to their findings, a former president of the Supreme Court of Vienna, who was involved in previous inquiries into the truth about the Kampusch case, agrees there are 'serious doubts' about whether the kidnapper killed himself.

Ernst Holzapfel (pictured) was a business partner and friend of Wolfgang Priklopil. Though Holzapfel has denied being anything more than a business partner of Priklopil, the two men are said to have become friends when they were apprentices at Siemens, the electronics giant, and would go out drinking after work

This, of course, throws up plenty of troubling questions. If Priklopil was murdered, why and by whom? And could this point to an even bigger — and sicker — scandal?

The mystery focuses on Priklopil's final hours, soon after Natascha escaped across those gardens in Strasshof an der Nordbahn, 25 miles from Vienna.

He was caught on film at a shopping centre with a man called Ernst Holzapfel, his business partner.

Holzapfel helped Priklopil escape police by picking him up at a shopping complex after the fugitive called and told him: 'I am in the Donauzentrum (shopping centre) by the old post office. Please pick me up. This is an emergency. Please pick me up.'

The kidnapping of Natascha Kampusch (pictured), who was snatched from the streets aged 10 and kept captive in a cellar for eight years, shocked the world

With a thousand police officers deployed to hunt down the kidnapper, Priklopil and Holzapfel were filmed on CCTV at the mall chatting intently. These were the last images of Priklopil alive.

In a police statement at the time, Holzapfel admitted driving the 'agitated' kidnapper around town, but maintained that he thought Priklopil was avoiding the police because he had fled from them after being stopped earlier for drink driving and was terrified of losing his licence.

'I tried to convince him that he needed to give himself up and that he would probably only lose the driving licence for a few months,' said Holzapfel.

'He promised to do that and got out. I simply could not believe [when he was told about the kidnapping by police] that he could be capable of doing something like that.'

Though Holzapfel has denied being anything more than a business partner of Priklopil, the two men are said to have become friends when they were apprentices at Siemens, the electronics giant, and would go out drinking after work.

They later set up a construction company together, with Holzapfel said to have been a frequent visitor to Priklopil's house throughout Natascha's captivity, which he also denies.

Priklopil's share of the business went to Holzapfel after the former's death.

Incredibly, he even met the imprisoned girl when Priklopil came to his home to borrow tools.

'He turned up with the young lady,' says Holzapfel.

'She stood with him in the entrance — he introduced her as an acquaintance. I offered her my hand and she said a very polite hello.

'She made a happy, relaxed impression. I didn't, of course, realise that it was Natascha Kampusch. It was only when I was questioned by the police that they showed me a photo and I realised it was her.'

This was a lie. As journalists probed the story, in 2009 Holzapfel had to admit that his friend had told him he had kidnapped and imprisoned Natascha — an admission allegedly made in the car shortly before Priklopil killed himself.

'I want to admit I deliberately, with regard to what happened on August 23, 2006 [the day Natascha escaped], did not say the truth because I feared the investigators would wrongly link me with the kidnapping.

'I was travelling in my Kia. He said to me: 'You are going to hate me, I am a rapist and a kidnapper.' He repeated it.

'He was really stressed. He seemed to be beside himself. He then explained he had kidnapped Frau Kampusch.

'The name didn't mean anything to me. He then told me that I knew her — I had seen her in the hall [of his own home].'

The house in Strasshof (pictured) where kidnapped Natascha was held in captivity for eight years

While Holzapfel denies any involvement in his friend's death, this has not stopped media speculation about what he might know about the suspected murder. Bild, the German newspaper, published a report headlined 'Was the kidnapper murdered?' above a large picture of Holzapfel.

Reporting that the focus had 'moved towards' him, Bild also repeated suspicions about his involvement in the kidnapping of Kampusch, though Holzapfel denies this and the police did not prosecute him after their original investigation.

Early suspicions about Holzapfel's involvement in the kidnapping were originally compounded by the fact that he was allowed into the house where Natascha had been held just hours after Priklopil had supposedly committed suicide.

Claiming that he went there to pick up tools, he has since been accused of removing computers and images of Natascha that would have implicated him in her captivity.

There have also been questions about why his first words when police arrived, just hours after Natascha escaped and before the story had become news, were 'Has he killed her?' — suggesting that he knew she was being held.

Intriguingly, there was a witness to Natascha's kidnapping in 1998. Ischtar Akcan, who was 12 at the time, saw Natascha being bundled into a van by one man, while another sat in the driving seat. The vehicle then pulled away.

'I know there were two men,' she told the Mail. 'The second man remained in the driving seat the whole time. They saw me, too. They knew I was a witness. In all those years she was gone I feared they would come back for me.'

Austrian police released a photograph of the room where Natascha Kampusch stayed in Strasshof

Who was this second man? We don't know.

Though Ischtar gave a statement to police at the time, her claims were ignored. 'Police told me: 'You made a mistake, didn't you?'; 'You couldn't possibly have seen a second man from where you were standing, could you?'; 'You saw a second van nearby with two men and mixed it up, didn't you?' '

Perhaps an even more disturbing aspect of this sprawling tale is the fate of a police investigator in charge of the Kampusch case, who died in mysterious circumstances after telling his brother he was on to 'something big'.

Colonel Franz Kroll was found dead on the balcony of his apartment, with a gunshot wound to the head and his service revolver lying by his feet. Alongside it was a suicide note in which he allegedly wrote about 'intolerable' work and family problems.

Yet independent investigators have rubbished claims that he, too, committed suicide.

His brother Karl believes he was murdered because he knew too much and had compiled files on others allegedly linked to the case.

This refers to long-standing rumours that, rather than acting alone, Priklopil was part of a paedophile network. There have been reports in the German media that he had links to this underworld, reputedly used by the rich and powerful in Austrian society.

Natascha had a television and a desk in her room in Strasshof, where was held captive for eight years

Indeed, it has been confirmed that Priklopil was in regular telephone contact with a pornographer and a paedophile group.

Certainly, Karl Kroll believes Priklopil was not acting alone.

To add to the intrigue surrounding this story, handwriting experts have suggested that the suicide note found next to Priklopil's body by the railway line bore more similarities to Hozapfel's writing than the dead man's.

Oddly, too, it was later revealed that Holzapfel shared more than 100 phone calls with Natascha after she had been released, despite claiming to have been introduced to her only briefly during her captivity.

So, what is going on? Would Natascha Kampusch really cover up the truth about the involvement of another man in her ordeal? Or did she just want to talk to someone who had known her captor?

Perhaps the clues can be found in her childhood. She grew up on a poor estate after her mother and father divorced.

Her mother was a party-loving single woman who often brought men home. Her father, a baker and heavy drinker, was seldom around, except for holidays.

The ten-year-old's home life was tough. So, after she was snatched from the street, her kidnapper regularly taunted her that her parents had sold her to him — a classic twisted technique used by paedophile kidnappers to emotionally manipulate and control their victims.

Certainly, Natascha has never repaired relations with her father, from whom she remains estranged. Perhaps this is because he, too, believes his daughter has never told the whole truth about her captivity and the involvement of others.

In 2006, she told astonished detectives she had been imprisoned in a cellar under a garage for eight years (pictured), where she was beaten, raped and treated like a slave

'There is something between us and that something is the truth of what happened — on that day, in that house and afterwards when she was returned to us,' he told us.

'It is my belief that until Natascha herself recognises that truth, it will always remain between us.'

Oddly, it was Natascha who first raised the possibility of others being involved.

In her biography, she talks more than once about a third person and that Priklopil told her: 'I'm going to take you in the woods and I'm going to give you over to the others. After that I won't have anything else to do with the business.'

One curious detail comes from what Natascha told police about the hours immediately after she was seized — she demanded to know the name of her kidnapper, she said, and the man driving her away claimed to be Ernst Holzapfel.

She has also spoken of threats made by Priklopil soon after she was taken that people would come to the cellar where she was being held and 'do things' to her.

Nor has it ever been explained why she was in contact with her kidnapper's business partner after she was freed, making all those phone calls to him in the months after she escaped.

Police sources have also claimed that, far from being imprisoned in the cellar, Natascha was regularly taken on days out by Priklopil.

These included trips to the shops and one outing to nearby ski slopes. Natascha maintains that she was too terrified to alert anyone while out with her captor, fearing he would kill her if anything went wrong.

She has remained an enigmatic figure since she was freed. After buying the house in the nondescript town where she was held for eight years, she has written a book and advised on a film about her case, making more than £6 million. She lives as a virtual recluse.