Father forced daughter to have 7 incestuous children

In a news that is shaking people to the core, it was revealed that a man in Austria, a father had a forced incestuous relationship with his daughter for a period of 24 years and had 7 children with her. This man, 73-year-old Josef Fritzl in the city of AMSTETTEN, Austria had built up a whole underground cellar system in his house in which he had forced his daughter into when she was 18 years old, and then kept her there for 24 years; during this period they had 7 children out of which 1 died, 3 of them the man adopted along with his wife (who lived with him in the same house but who did not know about this under-ground cellars), and the other 3 had never seen the light of day:

Three children freed from a cellar in which their mother had been imprisoned and raped by her own father for 24 years had never seen daylight, police in Austria have confirmed. The main question reverberating from the small Austrian town: How could a man keep his daughter locked in his basement for 24 years, where she gave birth to seven of his children while her mother and three of those children lived upstairs without an inkling of the horrors in the cellar?
Fritzl explained Elisabeth's disappearance by saying she had run away from home, a story backed up by letters he forced Elisabeth to write, including one that begged her parents not to look for her. Other letters made it seem the missing daughter had left the three children on the parents' doorstep -- when in fact they had been born in captivity in the family's basement.

This is horrific news; one wonders as to the depravity of the human soul that can do things like this - doing this with a stranger is bad enough, but doing this with your own daughter is like a scene out of hell.