Hunt for more dungeons at 'House of Horror'

AMSTETTEN, Austria (AP) -- Investigators were using sonar technology to check the yard of an Austrian man who held his daughter captive for 24 years to ensure that no more underground dungeons exist on the property, police said Friday.

Leopold Etz, chief of homicide investigations for Lower Austria province, said investigators are also widening their questioning of more than 100 people who lived in Josef Fritzl's house.

Those people lived in the building over the more than two decades that Fritzl held his daughter Elisabeth prisoner in a secret dungeon, fathering seven of her children.

Others who have come forward saying they knew the 73-year-old Fritzl are also being questioned. "We're casting a wide net. ... It's a lot of work," Etz said.

Fritzl's elaborate crime came to the attention of authorities April 19, when one of Elisabeth's daughters, 19-year-old Kerstin, was admitted to a hospital suffering from an illness linked to an unidentified infection.

Baffled doctors appealed on TV for Kerstin's mother to come forward because they needed information from her about her daughter's medical history. Fritzl then accompanied Elisabeth to the hospital April 26, and her story came to light.

Etz also said authorities were trying to verify whether a mechanism existed to pump gas into the dingy, windowless rooms where Elisabeth lived with Kerstin and two of her sons, as Fritzl had claimed during initial police questioning.

Authorities have said the house had an official gas line, and there was no reason to believe that Fritzl's threat was anything more than an attempt to keep his captives from trying to escape.

Police Col. Franz Polzer, who is leading the criminal investigation, said investigators have determined that the entrance to the dungeon was protected by a reinforced double steel door that opened and closed using a remote control. Watch a former tenant describe loud noises from the cellar »

Investigators 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," Polzer said.

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

A son and two daughters of Elisabeth by Fritzl were removed from the cellar by him when they were babies. He and his wife, Rosemarie -- who was told that Elisabeth had abandoned the children -- officially adopted one and were granted custody over the others. A seventh child died as an infant, and Fritzl has confessed to burning its body in an incinerator.

Fritzl faces up to 15 years in prison if convicted on rape charges, the most grave of his alleged offenses. However, prosecutors said Tuesday that they were investigating whether he can be charged with "murder through failure to act" in connection with the infant's death. That crime is punishable by up to 20 years in prison. E-mail to a friend

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