Austrian investigators disclosed more information about the complex underground dungeon in which Josef Fritzl sequestered his daughter and three of their children.

Fritzl, 74, began raping his daughter when she was eleven or twelve years old. Police officers who work on the case think it is then that he started planning how and where to build the cell. The dungeon was not recorded in any of the building’s plans and had only two entrances, one of them being electronic.

The story of this family’s captivity was made public about two weeks ago, when one of Fritzl’s granddaughters, Kerstin, fell unconscious and was taken to the hospital. Josef Fritzl kept his daughter, Elisabeth, locked for 24 years beginning with 1984, when the woman was 18.

As she gave birth to children, they were also kept imprisoned, except for three of them. Fritzl lied to his wife, Rosemarie, that their daughter Elizabeth had left these three on the doorsteps. The other three were kids were kept prisoners until recently and now find themselves in a clinic outside Amstetten, west of Vienna, where the family used to dwell.

Investigators deem this man as having some mental disorders and think he raped his daughter and turned her into a sort of wife because he wanted to rebuild the frames he once had with his wife. They suspect him to have raped his granddaughter Kirsten too.

The 74-old-year man is now in prison, refusing to go out of the cell. After visiting him, his lawyer Rudolf Mayer told the Daily Telegraph: "He's ashamed. He regrets what he has done. He wants a psychiatric expert to look into his soul. He is ill,” as telegraph.co.uk quotes. The convict will plead insanity.