Dungeon house police use sonar to check for more secrets

Police used sonar today to search the home of dungeon father Josef Fritzl to ensure no other underground prisons exist.

Leopold Etz, chief of homicide investigations for Lower Austria province, said they were also questioning more than 100 people who lodged in Fritzl’s house over the 24 years he held his daughter Elisabeth prisoner, fathering seven of her children.

Others who have come forward saying they knew 73-year-old Fritzl were also being questioned.

“We’re casting a wide net. … It’s a lot of work,” Mr Etz said.

He also said they were trying to verify whether a mechanism existed to pump gas into the dingy, windowless rooms where Elisabeth lived with three of her children, as Fritzl claimed during police questioning.

At the moment they believe Fritzl’s threat was nothing more than an attempt to keep his captives from trying to escape.

Police colonel Franz Polzer, who heads the criminal investigation, said experts working in the underground rooms had to take frequent breaks due to a lack of oxygen.

“We are trying to think of some way to improve the air circulation.”

Former tenants have said Fritzl told all residents of his apartment house in Amstetten that the basement was off limits and they were not allowed to take photos in the area. Anyone who broke that verbal agreement was threatened with eviction.

Elisabeth’s three other children by Fritzl - a son and two daughters - were removed from the cellar by him as babies.

Fritzl and his wife, Rosemarie, who was told Elisabeth had run off and abandoned the children, were granted custody over them. A seventh child died as an infant and Fritzl has confessed to burning its body in an incinerator.