The family of an Austrian man who imprisoned his daughter for 24 years and fathered seven children with her have been united for the first time in what doctors described as an "astonishing" gathering.
Josef Fritzl's daughter Elisabeth emerged from the windowless basement where he had locked her up with three of her children and was reunited on Sunday with three other children from whom she had been separated shortly after birth. A seventh baby died in the cellar after it was born.
"They met each other on Sunday morning and it is astonishing how easily it worked that the children came together," Berthold Kepplinger, medical director of the Provincial Clinic of Lower Austria, told a news conference on Tuesday.
"The children are quite well," Kepplinger said.
Around 200 residents of Amstetten, the town where Fritzl constructed his "house of horrors", held a rainy candle-lit vigil in support of the family in the town square.
"The outside world seems to think Amstetten is a terrible town, and that people in the community do not care for one another. We want to show this is not true," said organizer Elisabeth Anderson.
Austria's justice minister presented a bill on Tuesday to strengthen the country's "victim protection law", particularly in matters of sexual abuse.
In a case that has shocked Austria and the world, Elisabeth, now 42, spent nearly a quarter of a century without seeing sunlight with her daughter aged 19 and two sons aged 18 and 5.
The three other children -- two girls and one boy -- lived in the house above the cellar with Fritzl and his wife Rosemarie, who also had seven children of their own.
Kepplinger said that his clinic had a school where Elisabeth's children could be educated as part of their recovery process, and the three who had been locked up in the cellar could read and write, although not very well.
"The reunion between Elisabeth and her mother Rosemarie had also been astonishing," Kepplinger said.
"DNA tests confirmed that Fritzl, a 73-year-old retired electrical engineer, was the father of all six surviving children his daughter had born," police said.
Prosecutors were now investigating him over the death of the seventh child, whose remains he had burnt in a furnace, and said that he could be charged in connection with the child's death.
"Josef F. is being investigated for murder by failing to render assistance," prosecutor Peter Ficenc told Reuters, adding that the pensioner was also being investigated for rape, incest and coercion.
"Detectives were still combing the 60 square metre (645 sq ft) cellar beneath Fritzl's home," Franz Prucher, head of security in Lower Austria, said.
"Down there it is just chaos at the moment. We have to go over every detail very carefully," Prucher told Reuters.
Fritzl appeared before a judge in St Poelten, the provincial capital of Lower Austria, on Tuesday, and was ordered to be held in detention while police inquiries continued.
Officials said Fritzl said nothing on the advice of his lawyer. He was calm and had been put in a cell where he can be monitored in case he tries to commit suicide.
Elisabeth Fritzl says her father lured her into the cellar in 1984 and drugged and handcuffed her before imprisoning her.
Her fate came to light when the 19-year-old daughter became ill and was taken to hospital. Doctors appealed for her mother to come forward to give details of her medical history.
She was stable but critical on Tuesday, in an artificially induced coma and breathing with a ventilator.
"Our patient is in a severely life-threatening condition which resulted from a lack of oxygen caused sometime between Wednesday and Friday when she was admitted," Doctor Albert Reiter said.
The case has shocked Austrians less than two years after teenager Natascha Kampusch escaped from the basement near Vienna where she had been locked up by an abductor for eight years.
"There are a million unanswered questions," investigator Polzer told Reuters. "How could he manage to live with what he had done? How did he fool everyone?"
He said that he did not blame authorities for missing the case.
"Fritzl was a very cunning man. He not only fooled his wife, but officials, the police, everyone."
Fritzl brought Elisabeth and her remaining two children out of the cellar after the young woman was hospitalised, telling his wife their "missing" daughter had chosen to return home.
Elisabeth annd three of the children were kept in a complex which was in some places no more than 1.7 metres (5 ft 6 in) high and contained a padded cell, according to authorities.
Photographs show a narrow passage leading to rooms that included a cooking area, with children's drawings on the walls, a sleeping area and a small bathroom with a shower.