VIENNA, April 29 (Xinhua) -- Colonel Franz Polzer, head of the Lower Austria Land Office of Criminal Investigation, said Tuesday at a press conference that DNA tests showed that Josef F. was the father of his daughter's all six surviving children.

    "The results proved what we have always presumed and suspected," said Polzer, pointing out that "all six children of the 42-year old Elisabeth are undoubtedly fathered by her own father, the 73-year old Josef."

An Austrian police handout picture released April 28, 2008 shows a man suspected of keeping his daughter prisoner and abusing her for 24 years in the basement of a house in the small Austrian village of Amstetten. An Austrian woman said she was kept prisoner and abused by her own father for 24 years in a basement dungeon in eastern Austria, where she bore him seven children, Austrian police said on April 27, 2008.(Xinhua/Reuters Photo) Photo Gallery>>>

    According to Austrian media, so far the investigation showed that Josef was the only criminal of this case, "no evidence" that his 68-year-old wife was involved.

    Austrian Josef F. was accused of illegally jailed his own daughter Elisabeth since 1984 for 24 years in the basement beneath his two-story house in Amstetten (130 kilometers east from Austrian capital city Vienna), sexually abused her and fathered seven children by her.

A view of the Mauer hospital where the family of a man suspected of keeping his daughter prisoner for 24 years is receiving psychological treatment in Amstetten, eastern Austria April 28, 2008. (Xinhua/Reuters Photo) Photo Gallery>>>

    One of the children unfortunately died soon after birth and the body was burnt by Josef F. Three of them, aged 19, 18 and 5 respectively, had been locked with Elisabeth since birth and had never seen sunlight. Three other children were adopted and brought up by Josef and his wife.

    Josef even said that the children he adopted were abandoned by his missing daughter, who was not capable to raise her own kids.

    According to Elisabeth, she was firstly sexual abused by her father Josef when she was 11 years old and had been locked in the basement since she was 18. And 24 years ago Josef allured her into the cellar, drugged and handcuffed her.

    Soon after that, he even forced her to write a letter, saying that she had decided to run away from home. She since then has been registered as missing.

    However, the case was finally discovered when Elisabeth's 19-year-old daughter was severely ill and was sent to hospital at the middle of this month. Josef was therefore arrested last Saturday.

    The 19-year-old ill daughter of Elisabeth remains in serious situation and only "small slight improvement and certain stability" could be seen. Moreover, her artificially induced coma would continue for several more days, according to the doctor Albert Reiter who is treating her.

    The newest DNA tests also showed that one of the letters wrote by Elisabeth was not sent by herself, but by Josef. Traces were found on the being-stuck stamp and the envelope.

    Further investigations are still in progress. 14 days later, a proofs-verification will be held in St. Poelten, the provincial capital of Lower Austria.