AMSTETTEN, Austria -- The shocking case of a man who imprisoned and sexually abused his daughter prisoner in a dank cellar for 24 years only came to light when one of seven children born of that abuse fell gravely ill in mid-April.

• April 19: The woman, Elisabeth Fritzl, now 42, begs her father, Josef Fritzl, 73, to take the eldest of the incest children, 19-year-old Kerstin, to hospital. Fritzl's story is that Kerstin, who has never left the dungeon or seen the outside world, was left on his doorstep by Elisabeth, who he claims had run away to join an obscure religious sect 24 years ago.

• April 21: Doctors, unable to diagnose Kerstin's mysterious but life-threatening illness, alert the police who launch a search and a television appeal to locate her mother so that the doctors can make a better diagnosis.

• April 22: Police take mouth-swabs from the three incest children who were officially adopted by Fritzl and are living as his "grandchildren" in the house, as well as from both Fritzl and his wife, Rosemarie, 69.

• April 25: Elisabeth sees the television appeal from the 60-square-metre (646 square feet) dungeon where she has lived for nearly a quarter of a century and begs her father to take her to the hospital in an attempt to save Kerstin's life. Fritzl gives in. He allows the two other "cellar" children (aged five and 18) to be moved upstairs into the family home.

• April 26: Fritzl and his daughter go to the hospital. Following an anonymous tip-off, police intercept the two near the hospital. Initially, they question Elisabeth who is suspected of having abandoned three children (the three who live upstairs as Fritzl's grandchildren). Only after police reassure her that she need never see her father again does she begin to tell them about her unimaginable ordeal. The children are taken with their mother to the psychiatric clinic of Amstetten-Mauer, where they have since been given their own cordoned-off section and round-the-clock care.

Fritzl is arrested.

• April 27: The case begins to be reported by local media in the morning. Authorities confirm the first details towards midday. Fritzl at first refuses to answer questions as police search for the hidden door to the dungeon. He begins to talk in the afternoon, finally giving investigators the combination to open the electronic lock on the door. Officers first enter the dungeon in the evening finding a number of rooms with ceilings just 1.70 meters (5.5 feet) high. In all, the cramped, windowless dungeon has three rooms measuring 60 square meters.

• April 28: Fritzl makes a full confession, admitting to imprisoning his daughter and fathering her children. He also admits to burning the body of one baby who died shortly after birth in a wood-fired boiler in the cellar. He is remanded in custody. Investigators say the case has largely been solved and say there is no indication his wife was an accomplice.

• April 29: On the advice of his lawyer, Fritzl decides not to make any further statements about the crimes he is accused of. DNA tests confirm he is the father of the six surviving children. In the evening, hundreds of people take part in an emotional candlelit vigil on Amstetten's town square to express their shock and their solidarity with the victims.

• April 30: Police say they are taking a second look at the unsolved murder of a 17-year-old woman in Upper Austria in 1986 in the light of Fritzl's revelations. He and his family were in the area at the time where they owned a guesthouse.

• May 1: Investigators say Fritzl had told Elisabeth that she and the children would be gassed to death if anything happened to him. Police experts examine the cellar to investigate his claim that gas would be pumped into the cellar. The threat may have simply been to intimidate his prisoners into not trying to overpower him, police say.

Kerstin is still critically ill in intensive care and has been placed in an artificial coma. Doctors would only say she was taken in with a serious infection.

Elisabeth, her mother Rosemarie, and the other five children remain shielded away from the media in a specially cordoned-off area of the hospital to give them time and support to adjust to their new lives in freedom.