A lodger who once lived in Josef Fritzl’s House of Horrors claimed yesterday that he had known that the Austrian electrician was sexually abusing his daughter Elisabeth.

Sepp Leitner, who lived in Mr Fritzl’s house for four years in the early 1980s, said in a television interview that a female neighbour had told him that her friend Elisabeth had been raped by her father.

According to Mr Leitner, the neighbour even helped Elisabeth to run away to Vienna but the teenager was tracked down by police and brought back to Amstetten at her father’s behest. “Elisabeth was repeatedly raped by her father. She could not take it to live at home anymore and tried to escape,” Mr Leitner told the Austrian private television channel ATV.

“She had taken sleeping pills and went to Vienna. But the police found her and they, or her father, brought her back home.” Mr Leitner did not explain why he and the unnamed neighbour failed to alert the police about Elisabeth’s plight, though he hinted darkly at their fear of the landlord’s “revenge”. Mr Leitner said that he was still tormented by nightmares.

The Fritzl home in Amstetten is full of mysteries. It is a physical labyrinth that mirrors the convoluted plans, frustrations and desires inside Mr Fritzl’s mind. Sausage, fresh milk and cheese, for example, would disappear overnight from the fridges of the tenants rather as if the little people from The Borrowers were foraging for titbits.

The real reason was that Mr Fritzl would use his master key to slip into the tenants’ flats to pilfer provisions for Elisabeth and their three children. That was on the days when he did not have time for a shopping expedition. “I took care of them all,” Mr Frizl told police in his first (and only) interrogation. “I meant well.”

The rest of the family probably sees things differently. This man stole the childhood of at least three of his children – one of whom is still fighting for her life in hospital – lied to and manipulated the others, and raped and humilated his own daughter for a quarter of a century.

The sheer relief of the reunited Fritzl family, sheltered in a clinic, tells its own story: they have all been living in fear, and that fear is now subsiding. Mr Fritzl’s dark, hidden life seems to have been – in his mind alone – steered by a twisted love for his daughter Elisabeth, whom he called Liesel.

He started to abuse her when she was 11, in 1977. She was a pale, proud red-haired girl, the only child not to bow to her father’s snarling, changing moods. Her elder siblings kept their heads down, vowed to get married and leave the house as quickly as possible.

Their mother, Rosemarie, seemed not to notice that there was something odd in the tense, bickering relationship. The following year Mr Fritzl successfully sought building permission to extend his cellar and make a bunker that could resist nuclear fallout. Was there already a plan to imprison his daughter?

Elisabeth started to run away from home – once to Vienna, as the lodger suggests – and was beaten when she returned. At 16 she left home to work as a waitress and live in a hostel. Either because he was afraid of her betraying the sex secret, or because he couldn’t stand to lose her, Mr Fritzl decided that she should disappear. The calculating part of the Fritzl mind came again into play: he waited until she was 18 before drugging and handcuffing her. At this age she became just another adult missing person.

The abduction seems then to have been about control – breaking the will of a daughter who defied him. Mr Fritzl had reportedly raped before but sexual possession appears to have been only part of the equation. Part of him became engrossed in the mechanics of deception. Most of his ruses would not have worked in other societies but were enough to fool the Austrian bureaucracy.

He persuaded the community that Elisabeth had joined a Satanic sect and that over a decade she had dumped three children on his doorstep. When asked about her he would shrug and say that Interpol was on the case. “When Elisabeth’s third child was laid at the door we asked Sepp [Fritzl’s nickname] if maybe he shouldn’t try to find out about this sect,” says Christine R, sister of Rosemarie. “His answer was: ‘No point’. His word was law.”

Below stairs the signs suggest that he was beginning to see Elisabeth more as a lover. On his Thailand holiday in 1998 a video showed him buying a dress for a slim woman. “My secret girlfriend,” he told his travelling companion, “Don’t tell the wife.” Throughout the ordeal, Elisabeth probably drew her strength from her maternal instinct, her readiness to defy her torturer to protect her children.

There were times when Mr Fritzl did not need much persuading; he dutifully took her shopping lists and ultimately agreed to let her out of the dungeon to shield their critically ill 19-year-old daughter. Now Josef Fritzl is sharing a small prison cell with a man accused of attempted murder. He enjoyed an hour’s walk in the sun-dappled exercise yard – an incomparably more privileged existence than he allowed his captive family.

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