Josef Fritzl is to see his "dungeon family" for the first time since his arrest, when his daughter presents evidence on her 24-year ordeal of sex abuse and imprisonment.
Elisabeth Fritzl, 42, will be questioned by a judge, prosecutors and her father's lawyer in a court session which will be beamed to her father via video link.
Doctors treating Elisabeth Fritzl and her children have confirmed that following a month of therapy her condition has improved drastically and that she would be able to give evidence, although it is possible that a psychiatrist would be present during the questioning, which is due to happen in early July.
Her children, aged five to 19, will also be questioned at a later stage.
Fritzl, 73, confessed to imprisoning his daughter Elisabeth in the cellar of his home in Amstetten for 24 years and fathering seven children with her following continuous sexual abuse. One of the children died at birth and Fritzl burned his body in an incinerator.
The family's testimony is necessary for prosecutors to complete their case against him, who is facing a string of charges including manslaughter, rape and incarceration and is expected to appear in court in autumn.
His family will however not have to face him at the hearing and they are expected to give evidence either during pre-recorded sessions or via video conference.
The hearing in the regional capital St Polten's court is expected to be closed to the public.
More than 100 people have been questioned by police and prosecutors relating to the case, most of them relatives, neighbours, friends and work colleagues of the Fritzl family.
Christiane Burkheiser, the prosecutor in charge of the case, has questioned Fritzl two times already, and he is said to be "co-operative".
Fritzl is also being examined by a forensic psychiatrist who is visiting him in prison to determine whether he is fit to stand trial.
* source from Telegraph uk