Fritzl's lawyer Astrid Wagner told the Mirror: "We will start an action in March and call for parole and if the court rejects it we will appeal and given his condition, I believe he will be released by next year.
After finishing the building work, on August 28, 1984, Fritzl forced Elisabeth to help him drag a 300kg concrete and steel door down to the basement and fit it.
Fritzl was jailed for life in 2009 after locking his daughter, Elisabeth, in his basement lair for 24 years.
Sixteen years ago, Fritzl was incarcerated for incest, rape, coercion, false imprisonment, enslavement and the negligent homicide of one of his infant sons.
Ms Wagner, who also helped the monster write a book in 2023, said Fritzl has Alzheimer's disease and passes his days in his cell reading and watching TV.
