The "house of horrors" in Amstetten looks quite nondescript
Austrian police say an elderly man has confessed to imprisoning his daughter in a cellar for 24 years and fathering her seven children, in a case that has shocked the nation.
What is the accused alleged to have done to his family?
The daughter who was held captive, Elisabeth Fritzl, said her father, 73-year-old Josef Fritzl, incarcerated her in the cellar when she was aged 18. He allegedly drugged and handcuffed her.
Police say he has admitted beating her and sexually abusing her repeatedly. He also told police that he fathered her seven children, the youngest of whom is now five. Three of the children were locked up in the windowless cellar with Elisabeth and were kept there from birth. Police say Mr Fritzl admitted having burnt the body of one baby who died shortly after birth.
The other three children were raised by Elisabeth's parents - Mr Fritzl and her mother, Rosemarie - upstairs. They went to school and Austrian officials say social services were led to believe their circumstances were quite normal. Rosemarie allegedly knew nothing about the inmates in the cellar. Rosemarie had also borne Josef seven children.
Elisabeth, who is now 42, disappeared in August 1984. She was listed by the police as missing. It is reported that the three children taken in by the grandparents were left on the doorstep in successive years, with notes supposedly sent by Elisabeth.
How did the case come to light?
On 19 April the oldest child incarcerated with Elisabeth, 19-year-old Kerstin, fell seriously ill and was admitted to hospital. Elisabeth was very worried about her and persuaded Mr Fritzl to let Kerstin go to hospital, where she arrived in a coma. Hospital staff then alerted police, and the search began for Elisabeth. Mr Fritzl let her and the other two inmates - Stefan, 18, and Felix, five - out of the cellar.
What were conditions like in the cellar?
The two-storey house - quite ordinary from the outside - is in the quiet town of Amstetten, west of Vienna.
The cellar is reached down a narrow concealed hallway
Police found that Mr Fritzl had installed a reinforced concrete door to lock up the inmates in the cellar. It could only be opened by a remote control electronic device with a numerical code - and Mr Fritzl kept hold of the device. The door was hidden behind shelves.
The cellar was divided into cells - some parts were no more than 1.70m (5.6ft) high. A narrow corridor led into the cellar, which had a cooking and sleeping area, a small bathroom with a shower, and a padded cell. A tube provided ventilation.
Police say Mr Fritzl is a trained electrician, quite capable of having installed the remote-controlled door himself.
How are the children now?
The Austrian authorities have put the six children into care. Social workers say the five-year-old is "in excellent health". There are no details on the health of the others, because of Austrian privacy rules. Experts believe they may have suffered serious trauma, requiring specialist treatment.
What is especially puzzling about the case?
Austrians are baffled at how Mr Fritzl managed to dupe so many people for so many years, leading a double life. They are also amazed that his wife Rosemarie knew nothing about the true ordeal of Elisabeth at the hands of her husband.
Police say Mr Fritzl simply repeated the story that Elisabeth had disappeared - even after the children were born. But police are puzzled about the way he managed to provide food and other goods for the captives without raising suspicions. He has said that he went shopping outside Amstetten, alone in the evening.
Police think his captives were physically weak and powerless to confront him, as he dealt with them harshly.