She was kidnapped by her father, imprisoned in a cellar for 24 years and had seven babies by him, but Elisabeth Fritzl survived thanks to her devotion to her children. Fears are growing, though, that a transition to normal life could prove impossible, reports Caroline Davies in Amstetten

They won't have told her yet; it is much too soon. Any hopes that Elisabeth Fritzl may have of living a normal life with her children, funded by compensation from the father who imprisoned and repeatedly raped her, will be in vain.

Yesterday it was revealed that Josef Fritzl, the 73-year-old grandfather who incarcerated Elisabeth in a dank dungeon for 24 years beneath the family home and fathered her seven children, is financially ruined, with millions of euros in debts.

As Fritzl was moved to solitary confinement for his own safety, his heavily mortgaged property empire was on the brink of collapse, taking with it any dreams of a haven where Elisabeth and her children could find happiness.

It is a cruel blow for a daughter who still can offer no clue as to why her father held her captive in a windowless bunker beneath the grey, three-storey townhouse at Yppsstrasse 40, in the small town of Amstetten. 'I don't know why it was so,' she has told detectives. 'My father simply chose me for himself.'

Today she and her children are a few miles away from their dungeon home in the Clinic Mostviertel, where they have begun a long and painful journey towards rehabilitation that experts estimate could take eight years.

Elisabeth and her children have their own unique traumas to resolve. Half are the 'upstairs family' - Lisa, 16, Monika, 14, and Alexander, 12 - all fathered by Fritzl in the cramped chambers he dug out beyond his cellar. All three were taken in as babies by him and raised by his wife Rosemarie, 68, after seemingly just appearing, one after another, on the doorstep of the family home. Fritzl would tell everyone that their mother had run away to join a sect, dumping them with her parents because she could not care for them herself.

Then there is the 'downstairs family' - Kerstin, 19, Stefan, 18, and Felix, five - who remained in the tiny prison, never once seeing daylight and knowing only four other faces in their whole lives. Kerstin is comatose in hospital, suffering from renal failure. It was her life-threatening illness that would eventually betray Fritzl's monstrous secret.

Her two brothers are stooped, anaemic and barely able to communicate in anything other than their own peculiar growling language. A seventh child, Alexander's twin, died three days after birth, his body incinerated by Fritzl in the house's furnace.

Perhaps the worst fears are for Elisabeth. She is said to be 'deeply distressed', agreeing to talk to doctors and detectives only on the promise that she will have no further contact with her father. At the age of only 42, her crudely cut hair is completely white, her lips are shrunken around toothless gums, her face is deeply lined, her body painfully thin, her skin almost transparent. According to a forensic psychiatrist, Dr Guntram Knecht, she has been 'destroyed by all means'. Of all those Fritzl damaged, she was the only one to know she was a victim. If she can live with her children again, 'it will be because of her desire to be a mother,' he said.

Police photographs of the labyrinth of cellar rooms show narrow, stone-lined passageways, uneven floors and ceilings no higher than 5ft 6in. There was an ancient cooker, washing machine, freezer, as well as a television, video and radio. A small area housed a lavatory, sink and tiny shower. All the rooms were lit by harsh strip-lighting.

Poignantly, the pictures show how Elisabeth desperately tried to decorate the drab rooms for the sake of her children. On the grimy white bathroom tiles are a painted yellow snail with green shell, a purple octopus, a child's drawing of a flower and a fish, and stickers of stars and the sun - all of them things her 'cellar children' had never seen, except on the television, which was on all day.

No photographs have been released of the two tiny rooms where all four slept, or the rubber-padded room where Fritzl is believed to have raped his daughter away from the children. Was it in this room that she also delivered her babies without any medical help?

In all, the area measured 60 square metres, with Fritzl enlarging it as his family grew. But the area is so confined that police officers now examining it can work for only an hour at a time because of the severe lack of oxygen.

For Elisabeth there was no way out. Fritzl threatened that poisonous gas would be pumped in if they tried to overpower him. Police are checking this, along with his claim that an electronic lock on the door was designed to open automatically after a lengthy period. But they are sceptical. Fritzl enjoyed several holidays, including a three-week break in Pattaya, Thailand's sex-tourist resort, in 1998. Had he met with an accident, would his downstairs family simply have starved to death? Or was someone else helping to feed them?

Throughout the years, Fritzl lived his grotesque double life with relish. According to his wife's sister, Christina, he went to the cellar every day, usually at about 9am, allegedly to draw blueprints for machines he was selling. He would often spend whole nights there. He watched motor racing on television with his children and, in a bizarre attempt at playing the normal father, would buy toys for the children and play with them.

He bought Elisabeth clothes. Sometimes she chose them out of a catalogue. On other occasions he would choose them himself. Friends he holidayed with in Thailand saw him picking out a glittering evening dress and lingerie at a market - clearly much too small for his rotund, ageing wife. When he realised that he had been spotted, he joked about 'having a bit on the side'. Not for one minute did they suspect it could be his daughter.

But it is clear that he wanted Elisabeth, whom he called his Liesl, to dress up and parade around for him in the squalid, miserable cell he forced her to call home. Then, after raping her, he would settle down at the table while she prepared a meal and they would discuss the children's upbringing.

Some upbringing, but Elisabeth was determined to do the best she could. Though there were no books, she watched adventure films with them on television and made up stories about princesses and pirates. 'Their mother taught them some reading and writing, though Elisabeth herself lost much of her childhood knowledge because of the years of sexual abuse,' said Chief Inspector Leopold Etz.

Upstairs, the three other children continued to thrive, doing well at school, playing the trumpet, and were regularly seen out on Saturday nights, laughing and joking with their grandfather and Mami, as they called Rosemarie.

It was Elisabeth's primeval instinct as a mother desperate to save her child that finally led to her father's arrest. Realising that Kerstin was seriously ill, she demanded he take the girl to Amstetten general hospital. She slipped a secret, desperate note into her daughter's pocket, telling doctors that she had given her cough medicine and aspirin. 'Please, please help her. Kerstin is really terrified of other people. She was never in a hospital,' she wrote, adding a one-line message for her daughter: 'Kerstin, please stay strong until we see each other again.'

Upon reading it, doctors immediately made a TV appeal for her to come forward. When Elisabeth saw it, she ordered Fritzl to take her. And he did, accompanying her on the journey that would lead to his arrest in the hospital grounds and the end of her nightmare, which began a quarter of a century earlier on 28 August, 1984.

Elisabeth was 18 and working as a waitress at a motorway service station near Amstetten when she was lured to the cellar by her father that day. He knocked her out with ether and handcuffed her to a metal pole. For the first few weeks he kept her in the dark, visiting only to rape her and supply food. 'She had the choice, to be raped or to starve,' said a police source.

She was reported missing, but police, neighbours and supposedly even her own mother believed Fritzl's explanation that she had run away to join a sect. A letter, which she was forced to write, arrived at the house a month later, reinforcing the lie. It told her parents that she was making a new life for herself and that they should not search for her.

Fritzl singled Elisabeth out early. The fourth of his seven children by his wife, she was still an infant when, in 1967, he was sentenced to 18 months for climbing through an open bedroom window and raping a sleeping woman in the Austrian city of Linz, where he was working as an electrical engineer. Investigations have shown that he also had convictions for an attempted rape and for indecent exposure.

However, these were expunged from his records 15 years later, in line with Austrian law. Social workers found no trace of the convictions while rubber-stamping the paperwork that would allow him to adopt one of Elisabeth's children and foster two others. By then he was a seemingly successful landlord, renting out flats at the family home and at four other premises he owned, as well as running a lakeside pub and campsite. Family friends remember Elisabeth as a 'very withdrawn and shy' child. Paul Hoerer, 69, who first met Fritzl on holiday in 1973 and visited the Amstetten house several times, noticed that she 'got a slap for every small thing'.

Though domineering and despotic with all his children, Fritzl appeared to treat Elisabeth even more brutally than her siblings and Hoerer got the impression that 'he did not like her very much'. When she reached the age of 11, the abuse started. From then on Elisabeth would be raped by her father regularly: in his car, during forest walks, even in the same cellar that would become her prison.

At 16, she twice attempted to run away from home, but each time was delivered back into her father's violent embrace by the local authorities. Three years later, there was no possibility of escape.

The chambers were so well hidden that police initially failed to find them until Fritzl guided them through five different rooms in the cellar, to his workshop. There, concealed behind shelves laden with paint cans and containers, was a 3ft-high, reinforced, 660lb concrete door, secured electronically. Though adamant that he had no accomplice, police are struggling to explain how he could have fitted it alone.

But why did he choose to release the three 'upstairs' children and not the others? A likely explanation is that when Kerstin and Stefan were born Fritzl believed it was possible they could be secluded for ever. But as the raping continued, and Elisabeth's family grew, he simply ran out of room. It was too late to move the two eldest, who by now had memories of the place and of their mother and him together. So they were condemned. By the time Felix arrived, he may have believed that his wife was too old to cope.

There are signs that Fritzl was planning to release them. He had made Elisabeth write a letter in which she said she wanted to come back, 'but it's not possible yet'.

'Perhaps he was aware that he couldn't keep the thing going forever,' said Colonel Franz Polzer, police chief of Lower Austria. Or perhaps he was no longer attracted to his anaemic, ailing daughter who now looked as old as her mother.

His plan seems to have been that Elisabeth would appear to return suddenly from the sect and that the dreadful physical condition of her and her children could be attributed to her treatment there. But this deceit was denied by Kerstin's illness.

Today the family is slowly acclimatising in a special area set aside for them at the clinic. Elisabeth and her mother are said to have have wept for hours together, with Rosemarie saying over and over: 'I'm so sorry. I had no idea.'

After their initial delights at seeing the sun for the first time, and riding in cars, Stefan and Felix can clamber back into the dark confines of a special container set up in the clinic to help them adjust to life outside.

Felix often crawls in there, and sits humming an unknown melody to himself. Police believe his mother used it to soothe him to sleep.

'It can't be called a good-night song really, as there was never any night in the cellar,' said Chief Inspector Etz.