‘Light out. Rape. Light on. Rape. Birth. Death. Rape’

She pulled back the lid of the brown cardboard box, and invited the jurors to take a sniff at the objects inside. It was, said Christiane Burkheiser, a chance for the jury to experience for themselves the rancid stink that pervaded every inch of the underground prison beneath the family home in Amstetten, west of Vienna, where Josef Fritzl held his daughter for 24 years and allegedly raped her repeatedly.

It was one of the more dramatic moments of the opening on Monday of the long-awaited trial of the Austrian electrical engineer. No one in the public gallery could see what was in the box — children’s toys, books, clothing perhaps — but the crumpled looks on the jurors’ faces left little to the imagination.

The state prosecutor had felt the full impact of the cellar prison when she visited it herself. “I’ve seen the cellar dungeon twice,” Burkheiser said. “It has a morbid atmosphere, which starts with having to crawl in on your hands and knees through the 83cm entranceway. And it’s sinister. It’s really bad. It’s incredibly damp, a damp that creeps into you after just a few minutes.”

Fritzl sat listening impassively on a suede-upholstered chair, wearing grey trousers and a black and white check jacket that was slightly too large for him.

Minutes earlier he had shuffled into room 119 of the St Pölten district court, flanked by six police officers and clutching tightly at a royal blue folder to shield his face from the clicking cameras.

The 73-year-old looked a shadow of his former self as he walked across the creaking oak floor.

Gone were his healthy suntan and the confident gait shown in video footage of him on holiday or in snapshots enjoying barbecues in the garden — while his daughter, and the offspring he fathered during years of sexual abuse, languished beneath his feet.

Fritzl refused to answer the questions fired at him by two Austrian reporters.

“If you had your chance again, would you do it all the same way?” one reporter asked, provoking nervous laughter from the public gallery. Fritzl kept his shield in place, although at times he was seen to apparently grin as his grey moustache twitched behind the folder. When he finally sat after cameras had been ordered from the court, he placed the file on the table in front of him and held his hands to the side of his head like blinkers instead.

The Guardian was one of only two British newspapers represented in the small courtroom as Burkheiser, for 25 minutes, laid out her emotional arguments, sometimes using a laser pointer to indicate masking tape she had stuck to the walls of the wood-panelled courtroom to illustrate the narrowness of entrances, the low heights of ceilings that Elisabeth and her children had had to endure.

The space constraints and the damp were, she said, minor compared with the other hardships and sufferings. For years Elisabeth had had no sink, no warm water, no daylight. She had “got her air from the cracks in the walls”. Sometimes she went without light for days at a time — “no lamp, not even a torch or candles”. And there were also the repeated rapes.

“But do you know what the worst thing was?” she asked the jury of four men and four women. “The uncertainty: when will he return, when will he turn on the electricity, when will he go again, what will happen if he doesn’t return?” she said, reducing her voice to a whisper as if to maximise the impact of telling a scary bedtime tale.

She said they should not be fooled by Fritzl’s polite demeanour, the image he projected of “a nice old man from next door”. She said the trials of the cellar inhabitants were best encapsulated in a single paragraph, which she delivered in staccato fashion: “Light out. Rape. Light on. Mould. Rape. In front of the children. The uncertainty. Birth. Death. Rape.”

She detailed the births over 12 years of Elisabeth’s children, the three who stayed in the cellar and the three who were taken upstairs to live with their “grandparents” — Fritzl and his wife, Rosemarie. She also told of the birth in 1996 of a twin, Michael, who died after suffering from severe breathing difficulties, which she said would probably have been avoided had Fritzl sought medical help.

“That, ladies and gentlemen, is murder.”

Then turning to Fritzl, who has admitted disposing of the body in an incinerator, she squinted her eyes and, reducing her voice to a sibilant whisper, said: “Herr Fritzl, your own flesh and blood. To treat it that way?”

The accused moved his head slightly but did not appear to express any emotion.

Rudolf Mayer, Fritzl’s lawyer and a veteran presence at Austria’s more obscure criminal cases, urged the jury to take a less passionate view of his client.

“You need to keep emotion out of this,” he said, arguing that it was wrong to call him a monster, as he has repeatedly been referred to in the media.

“A man who put so much effort into keeping two families cannot be called a monster,” he said. “If I only want a daughter as a sex slave, I don’t let her bring children into the world. You’d let them starve,” he said.

In an indirect reference to the Belgian criminal Marc Dutroux, who kidnapped and murdered four girls in 1996, Mayer said the “Belgian case” was an example of monstrous behaviour, but it was unfair to put the label on Fritzl.

“When his eldest daughter was seriously ill, he put her in his Mercedes and took her to hospital,” he said, referring to Kerstin (19) whose hospitalisation last April caused suspicious police to close in and was the catalyst that brought Fritzl’s underground empire crashing down.

The charges