http://www.guardian.co.uk/world/2009/mar/16/josef-fritzl-cellar-austria-trialHe's admitted to rape but he's denying the murder charge.
The maximum sentence will be 15 years if he gets away with murder and 7 1/2 years if he's a 'good boy'. That is taking the piss! That's less than what Elizabeth had to suffer through! With or without murder what he did should merit life imprisonment!

Apparently the slavery charge is not appropriate! WTF? He used his daughter as a sex slave! The bastard deserves to be forcefully sodomised till he dies in prison!
The prosecution always try to get the charge that sticks, otherwise they lose the case and the guy walks away scot-free. Enslavement is very difficult to go for considering the technical definition of the term, he could probably wriggle his way out of "enslavement" because of old legal definitions (it's not exactly a hotly contested legal issues and so the law probably goes back centuries).
THe murder charge is probably their best chance given the facts of the case, plus a rape or serial rape charge would get him out in less than 7 years.
Don't worry though, he's not exactly going to a local jail cell, he will suffer terribly at the hands of those inside the prison where he's going and will either be dead (close to it at least) or meentally broken by the time he comes out-if he's still alive at his 80th birthday, which isn't a common occurence in a prison.
He will get his just deserts, not as much as I'd like, but even if he's let out with 7 1/2 years, it won't be an easy ride.