As Josef Fritzl was led into a wood panelled Austrian courtroom, he seemed a shrivelled figure. For his re-entry into the world after almost a year of pre-trial arrest, he held a blue ring binder over his face, a visor against the flashbulbs of photographers but also an ancient symbol of shame.

"How do you explain yourself? How can you abuse your daughter for 24 years," asked Austrian television reporters, thrusting their microphones into the dock. Silence.

Mr Fritzl, the 74-year-old-engineer, did eventually speak, after the cameras were excluded from the courtroom. And the face was exposed.

The voice, confirming his identity and marital status, was reedy, had none of the deep timbre that had been associated with the man who fathered 13 children, seven of them in an incestuous relationship with his imprisoned daughter Elisabeth.

And the face — so tanned when he abandoned his entombed family for a month to take a holiday in Thailand — was parchment yellow, a prison complexion.

Mr Fritzl has been in detention for 323 days. His daughter, according to the charges read out in court, was in her dungeon for 8,461 days until her release last April.

Josef Fritzl is accused of raping, enslaving and imprisoning his daughter for almost a quarter of a century in a specially constructed bunker only 11 steps away from his living quarters.

He is accused, too, of fathering seven children by Elisabeth and allowing one of them to die as a baby. The murder charge could bring a jail sentence of 15 years, enslavement 20 years, massive coercion five years, deprivation of liberty up to ten years, incest one year.

As expected Mr Fritzl denied committing murder by neglect and denied enslavement — the two charges carrying the heaviest jail terms — and his defence lawyer, Rupert Mayer, stressed that it was wrong to describe his client as a monster.

"The exceptional aspect of this case is that my client did not behave like a monster," said Mr Mayer in an interview before the trial began. Yes, he held a woman against her will in a cellar and abused her, said Mr Mayer. This Mr Frizl had admitted to, in earlier police questioning.

"But the special point is that he chose his daughter for this role, that he created children together with her and looked after them," said Mr Mayer. "He bought them schoolbooks, celebrated Christmas and birthdays with them."

The prosecutor's indictment presented a less charitable picture of Mr Fritzl. The building engineer — who at one stage owned seven properties — was obsessed with control and was infuriated by the rebelliousness of Elisabeth.

It was significant that he pushed her into the dungeon, clamping a handkerchief with ether over her mouth and nose, as she was turning 18: the age at which she would have been free to go, to betray his secrets and take lovers.

The indictment cites the case of Elisabeth's older brother Harald who worked as a waiter.

When Josef Frizl once smelled alcohol on Harald's breath, say the prosecution documents, he broke his son's nose and refused to allow him to seek medical help. Mr Fritzl, say the prosecutors, ruled with an iron fist.

"In the dungeon he tied his daughter on the upper arms and tied her hands behind her back with an iron chain which was connected with a curtain trail to an iron pole behind the bed," said the indictment, quoted by News magazine.

In the early days of her captivity, he allegedly strapped a dog collar around her neck and led her to the improvised toilet. The highest point of the ceiling was 1.8 metres, forcing Elisabeth and her elder children, Stefan and Kerstin to stoop.

There was a double bed, where Elisabeth was regularly raped, a sink, a toilet, a cooking ring, plastic cutlery, a video recorder. Later the dungeon was expanded, a washing machine was installed, shelving for food so that Mr Fritzl could leave for extended periods of time.

There were important unspoken questions in the courtroom. Why did no one comment when Mr Fritzl broke his son's nose in public? Why was there no closer research when Mr Fritzl suddenly announced that his daughter had run away to join a cult? Why did no one register that Mr Fritzl was making double purchases, for his acknowledged upstairs family and for his hidden family downstairs?

Judge Andrea Hummer speaking on a podium that bore a wooden cross and two candles — almost like an altar piece — stressed that the trial would assess crimes committed against members of a family, "Not of a region, let alone a whole nation."

Austria, in other words, was not in the dock. Only Josef Fritzl.

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