The move comes after she was thrown out of the flat she was sharing with her daughter and her six grandchildren. The whole family has been put up there by the Austrian government, apparently to shield them from media attention.
The 42-year-old Elisabeth kicked her mother out as was furious that three of the children born to her during her captivity in the cellar kept treating Rosemarie their grandmother as their mother, local newspapers said.
Joseph Fritzl had moved three of his offspring through his daughter upstairs where they were brought up by him and Rosemarie. That the three should still keep calling their grandmother 'ma' proved galling for Elisabeth.
So peremptorily Elisabeth ordered her mother out. With no money, cut off from her family and with her 74-year-old husband in jail awaiting charges that might see him imprisoned for life, Rosemarie is said to be shattered. 'She has no idea where to go or what to do,' said a family friend.
The mother was moved into the psychiatric hospital with Elisabeth and the incest children after Fritzl's secret cellar was discovered in April this year.
Possibly the daughter is also skeptical whether her mother was not aware of what was going on downstairs, as she has been protesting all these days.
In a belated move, to please her daughter perhaps, the mother has chosen to divorce her domineering husband. Some reports said that she was doing so at the instance of Elisabeth herself.
The 69-year-old Rosemarie Fritzl was last seen picking up her private belongings from the home she lived in for over half a century with her husband. She has taken several pieces of furniture and has since been spending the nights at different places and living with relatives and friends, it is reported.
Christoph Herbst, the lawyer for the Fritzl family, said: "No-one from that family will ever want to live in that house again."
Not having worked since her early youth, Mrs Fritzl is only entitled to meagre benefits payments amounting to just over 200 pounds.