'Horror Father' Warned Captives That He Would 'Gas Them':

AMSTETTEN, Austria -- An Austrian man who held his daughter captive for 24 years and fathered her seven children repeatedly warned his captives that they would be gassed if they tried to escape, a spokesman for investigators said Thursday.

The revelation came as authorities also said that Josef Fritzl forced his captive daughter to write a letter last year indicating he may have been planning to release her from the windowless dungeon where she lived with three of their children.

Police Col. Franz Polzer said Elisabeth Fritzl wrote in late 2007 to her family, who believed she had fled to a cult, that she wanted to return home but "it's not possible yet."

Not only did he force her to write this letter, he pretended to be her in a 1994 phone call. I must say, at risk of offending some, you almost have to give this guy some credit. I'm quite impressed with time-locked doors and an entire house, essentially, built under his own. Don't get me wrong, he's a vile, disgusting man who should spend the rest of his life in prison - but he did manage to pull this whole charade off for more than a quarter century.

Officials are also looking into claims that there was a 'second man' who entered the cellar on several occasions. Other outlets are reporting that a neighbor may have heard 'knocking' and pleas for help from the victims but brushed them off and told no one. The most disturbing development comes from the UK Sun which says the children communicate with 'growls' and walk around on all fours 'like a monkey.' These children will never live a normal life...