April 29 (Bloomberg) -- Josef F., the Austrian who admitted having seven children with his daughter while holding her captive for 24 years, appeared before a judge today as police continue their investigation of alleged rape and incest.

``The judge extended the man's detention as he admitted the captivity and incest charges,'' Gerhard Sedlacek, a spokesman for the prosecutor in the Lower Austria province, said today. ``We are still investigating whether we will also charge him with murder, and the man disputes the rape charges.'' One of the seven children died after birth, he said.

The 73-year-old man imprisoned his daughter Elisabeth and three of their children in a 60 square-meter cellar, police said. The two had four more common children over the past 19 years.

The case, in the rural medieval town of Amstetten, is the third in Austria since 2006 where children have been held captive by a stranger or family members for years without being noticed. Rosemarie F., the 68-year-old wife of the suspect, Elisabeth's six siblings and the neighbors told investigators they didn't know anything about the captivity.

``One wonders how nobody inside or outside the family noticed that the father bought food and clothes for four more people,'' said Manfred Prisching, a professor of sociology at the University of Graz in southern Austria. ``People are more often told not to stick their nose into the affairs of others.''

In August 2006, 18-year-old Austrian Natascha Kampusch broke free from a basement prison in Strasshof near Vienna where she was held for eight years by a kidnapper. The mother, neighbors and a friend of the kidnapper had seen the girl and were told that she was a cleaning lady.

Being Questioned

Rudolf Mayer, a lawyer representing F., said he didn't object to the detention of F. while he is in talks with his client as to whether police claims about the confession are correct. He declined to elaborate further.

Blossoming rapeseed fields and silent tractors line the hills bordering Amstetten, a town of 23,000 people about 130 kilometers (80 miles) west of Vienna.

The town, known for its medieval square and copper pipe factory, lies in the middle of Austria's Mostviertel, where apples and pears are harvested for jams and juice.

From yesterday, Amstetten may become known more for the basement at Ybbsstrasse 44, a bunker-like concrete house in one of its residential neighborhoods. The prison was accessible only through an electronically controlled steel door. Inside the 1.7 meter high cellar were a bathroom, small kitchen and television.

Rosemarie F. knew nothing of her husband's double life, police officer Franz Polzer said yesterday.

Sadistic Hold

``It looks as if the man had a sadistic authority over his immediate environment that completely took away his family's ability to question anything he told them to do,'' said Max Friedrich, the head of the Clinic of Child and Adolescent Psychiatry at Vienna's Medical University.

Josef F. allowed three of the children to live above ground and attend school by saying that his daughter gave them up for adoption after running away to join a sect.

Their siblings lived in the basement. He burned the remains of one other child who died at birth, police said.

``The father must have built up a double life where he was the honest man to the outside while living out his absolute authority in his life at home,'' Friedrich said. ``The mother was completely dependent and didn't dare ask him any questions.''

Josef F. was an engineer by training and later worked for a machinery maker and a construction company, Austrian newspaper Die Presse reported today. Later, he ran a campsite and a rural restaurant in the Upper Austria region, the paper said.

He also bought and renovated houses to rent them out, according to Die Presse.

Sexual Abuse

In 1984, Josef F. made his then 18-year-old daughter Elisabeth write a letter in which she said she left the house because ``she couldn't handle her life,'' and joined a sect, police officer Polzer said. In reality, Elisabeth was being beaten and sexually abused, between bearing children.

Rosemarie F. didn't question her husband when he suggested the couple take care or adopt three of the children. Josef made his daughter write letters explaining that she couldn't care for the children.

Authorities began searching for Elisabeth on April 19 when a 19-year-old girl, believed to be her daughter, was admitted to the local hospital because of poor health. She is still in critical condition while all the other family members are getting psychiatric support.

The hospitalized daughter had a letter from her mother with her, asking for help. On April 26, police, acting on a tip from an unidentified person, stopped Josef F. for questioning as he approached the hospital with his daughter.

Elisabeth ``made a very confused and disordered impression,'' police said. After being assured that she would no longer be in contact with her father and that the authorities would take care of her children, she gave a ``comprehensive'' account of the past 24 years.

To contact the reporter on this story: Matthias Wabl in Vienna at mwabl@bloomberg.net; Jonathan Tirone in Vienna at jtirone@bloomberg.net.

Last Updated: April 29, 2008 07:28 EDT