Austrian police seek "House Of Horrors" answers

Fritzl, whom police described as "dynamic, bossy and authoritarian", had hidden the entrance to the cell behind shelves and only he knew the code for the concrete door.

The case unfolded when the 19-year-old girl became seriously ill and was taken to hospital with severe cramp caused by lack of oxygen. Doctors appealed for her mother to come forward to give details of her medical history.

Fritzl brought Elisabeth and her remaining two children out of the cellar, telling his wife their "missing" daughter had chosen to return home, police said.

Elisabeth agreed to make a thorough statement to the police after receiving assurances she would have no further contact with her father, who she said abused her from the age of 11.

Police believe Josef's wife did not know what happened to her daughter when she disappeared in 1984.

Fritzl had said Elisabeth had joined a sect and that she had left the children on the doorstep. He forced Elisabeth to handwrite letters to prove his claims, said the police.

(Writing by Ralph Gowling; editing by Ibon Villelabeitia)