Josef Fritzl, 73, of Amstetten, Austria had 14 children, seven by his wife, Rosemarie, 69, and seven by his daughter, Elisabeth, 42. Josef is now behind bars in what the Austrian press describe as the case of the house of horrors.

It all began 24 years ago in 1984 when Josef, an electrical engineer, kidnapped, drugged and imprisoned his 18-year-old daughter in the basement of their home in Amstetten, an industrial town 75 miles west of Vienna. He then told his wife that their daughter had run away from home. He kept her locked in a 540-square-foot prison of underground rooms, which he had previously built, some barely large enough to stand upright in. He had planned the dungeon meticulously and it was well soundproofed. The door to the prison was concealed behind shelves and secured with an electronic lock to which only Fritzl had the code.

While in captivity, Elisabeth Fritzl gave birth to the seven children by her father, one of whom died shortly after birth, which Josef disposed of in a furnace. Each time Elisabeth became pregnant, Fritzl delivered the children himself. Of the six remaining children he took three of them - Lisa, now 16, Monika, 14, and Alexander, 11 - out of the cellar after birth and came up with an elaborate charade to explain their sudden appearance to his wife. The other three children - Kerstin, 19, Stefan, 18, and Felix, 5 - were left to be raised by Elisabeth in his home-made dungeon.

Josef’s 18-year imprisonment of his daughter came to an end when Kerstin became seriously ill and had to be taken to hospital. Medical authorities at the hospital became suspicious and called the police. Josef was picked up, and later under questioning, revealed the existence of the basement prison. Police freed Elisabeth Fritzl and the two other children, all of whom were quickly put in the care of medical and mental health experts. Elisabeth, although “greatly disturbed“, agreed to give them a full statement - on condition that they made sure she would never have to see her father again. She claimed that she had been sexually abused by him since age 11. Fritzl appeared briefly in court and was sent to jail to await trial. He faces a15-year sentence if convicted of rape.

Senior police officer, Dr Franz Prucher, says the criminal case has shaken the force.

“We’re being confronted with an unfathomable crime,” Austria’s interior minister, Günther Platter, said as the details began to unfold. “This case is one of incomprehensible brutality and horror, the most shattering and serious case of its kind that has ever come to light in Austria.”

Questions were being asked by everyone from commentators and parents to psychologists and politicians, as to how what the Austrian press has dubbed the “house of horrors” case had come to happen in the small town of Amstetten.

“There are pressing questions raised by this monstrous crime which need to be put to a rich, self-satisfied society in which during a quarter of a century what was happening in the immediate vicinity went apparently unnoticed,” Petra Stuiber wrote in a commentary in the Austrian liberal daily Der Standard.

“How is it possible that no one ever heard or saw anything, how can it be that no one ever asked questions?” she wrote. “What does it say about neighbors, relations, acquaintances and not least about authorities who had anything to do with the family, that the perpetrator succeeded in ‘deceiving’ everybody?”

Local social services told the Austrian Press Agency that there appeared to be nothing suspicious about the family and that Mr Fritzl managed to explain “very plausibly” how three of his infant grandchildren had turned up on his doorstep. Even his wife, Rosemarie Fritzl, “had no idea” what was going on, according to the police, and was devastated to hear of her husband’s alleged crimes. She apparently accepted her husband’s explanation that Elisabeth had run off to join a religious cult at the age of 18 - and that over the intervening years dumped three babies on their doorstep with notes saying she could not cope.

Amstetten’s local governor, Hans-Heinz Lenze, told Austria’s public broadcaster ORF that the children had had regular visits from social workers, who never heard any complaints or noticed anything to arouse their suspicions. He said they were well-behaved at school and fitted in well with their classmates. The three were apparently unaware of their mother’s existence, let alone that their siblings Kerstin, Stefan and Felix were living below them. Mr Lenze also told ORF that Mr Fritzl had telephoned him last week and thanked him and the social services for looking after his family during his granddaughter Kerstin’s illness.

Josef Fritzl, who does have a criminal record, is believed to have spent time in prison in the 1960s for the assault and also has at least one other conviction, for arson, according to Austrian police. Prosecutors are understood to be trawling through court records to find details of his previous offences to see if they shed light on what they have described as his “unfathomable” actions to his own family. The revelation he already has a criminal record will increase the anger that his behavior could have gone undetected by social services for almost a quarter of a century. It also indicates his wife Rosemarie must have been aware - at least to some degree - of her husband’s sinister side.

Investigators are also desperate to determine how his victims could have been hidden away for so long from their neighbors and everyone else in the town, which has a population of just 23,000. They are said to be examining the padded walls of the cellar to work out whether the children’s screams could be heard by neighbors.

Meanwhile, residents refuse to believe Fritzl could have acted alone, while others cannot believe that the “normal” family were hiding such a horrendous secret.

Anita Fabian, a teacher in the town, said: “How is it possible that no one knew anything for years? This was not possible without accomplices.”

Guenter Pramreiter, who owns a bakery down the street from the Fritzls’ home said the couple were regular customers.

“They appeared normal, just like any other family,” he said. “I’m totally shocked. This was next door. It’s terrible.”

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