KEY POINTS:
An Austrian prosecutor says a man who held his daughter captive for 24 years in a cellar and fathered seven children with her may be charged with slavery.
St Poelten prosecutor Gerhard Sedlacek also says authorities hope to have a series of formal charges ready by the end of September and that a trial would likely begin in December.
Investigators say Josef Fritzl confessed to taking his daughter Elisabeth prisoner when she was 18, sexually abusing her and fathering seven children with her.