Meanwhile, investigators said they were now painstakingly trying to reconstruct the life of Fritzl, who had seven children with his daughter.

DNA tests have confirmed 73-year-old Josef Fritzl was the father of all six of his daughter’s surviving children and prosecutors are probing him for rape, incest, coercion and the death of the seventh child, whose remains he burnt in a furnace.

“Now the DNA tests prove he is both the father and grandfather of the children, we must reconstruct his entire life, piece by piece,” Franz Prucher, head of security in Lower Austria told Reuters.

“Who did he meet, where did he shop, where did he go? We have 24 years to cover,” Prucher said, adding further details would be given at a news conference later on Wednesday.

Amstetten officials say they do not blame local authorities for failing to discover the case earlier and say those who allowed Fritzl and his wife to care for three of Elisabeth’s children acted within the law.