Josef Fritzl, the Austrian man who imprisoned his daughter and fathered seven children with her during 24 years of sexual abuse, is likely to face manslaughter charges after a breakthrough in the four-month investigation against him.

The 73-year-old retired engineer and property developer kept his daughter Elisabeth, 42, a purpose-build dungeon in the cellar of his home in the town of Amstetten, where she gave birth to seven of his children. One of them — a twin boy, Michael — died three days after birth in 1996, and Fritzl burnt the body in an heating furnace.

Prosecutors had been unoptimistic about being able to chargeFritzl with the child's manslaughter, because of the time that had elapsed and the absence of evidence, together with his children's refusal testify against him. Now a neonatologist — a medical expert specialising in the newborn — has said that Fritzl must have been aware that the baby was in a life-threatening condition and that his life might have been saved by a medical intervention.

The specialist's confidential report has been leaked to a local magazine. According to News, the report says that the baby suffered from a “severe and life threatening condition” that must have been “obvious” even to a person without any medical knowledge. His ymptoms included severe breathing difficulties that worsened rapidly and culminated with his death about 70 hours after birth.

Quoting the neonatologist’s findings, News reported: “Josef Fritzl must have known that the child would die if he was not provided with adequate medical attention.”

The findings, which are based on the testimony of Elisabeth Fritzl, could now be used to bring manslaughter charges against her father, with a maximum life sentence if he were convicted.

News said that Ms Fritzl told the expert that her father did not react to the symptoms of their baby and ignored his breathing problems during several visits to the cellar after the baby was born.

According to News, Fritzl denied the accusations, saying that he had seen the baby for the first time only after the child had died. He was quoted as saying: “I only found out that I was father to twins when one of the children was already dead; my daughter Elisabeth then gave me Michael’s body so I could burry it.”

The charges against Fritzl should be compiled in the next the two months and the trial is to take place by the end of the year.

So far, the only testimony against him comes from his daughter Ms Fritzl, while her children have refused to give evidence against their father.

Fritzl selected three of his children – Lisa, 15, Monika, 14, and Alexander, 12, to live with his wife Rosemarie, 69, in their upstairs apartment. They had a normal life and excelled at school, while their three siblings – Kerstin, 19, Stefan, 18 and Felix, 5, were forced to live with their mother in the concrete bunker bellow and had not seen daylight until the case was revealed last April.

The three children who lived upstairs were supposed to return to school this week, but this wasy was made impossible by the numerous reporters who were waiting in fornt of the school building. They will therefore continue to receive private tuition at the secret location to which they have been moved in a scheme similar to that of a witness protection programme.

Times Recommends

• Riots as Zimbabwe turns off water supply
• Tourists told to stay away amid Venice floods
• Protest is no picnic for Carrefour customers