Josef Fritzl, the Austrian incest father, had forced his daughter to fulfill his sexual fantasies after making her watch porn films, it was revealed on the second day of his trial.
The jurors heard the pre-recorded evidence of Elisabeth, now 42. She was spared the ordeal of coming to court, but she has recorded her torment, which had started in 1984. The recordings run over 11 hours.
She said Fritzl would bring boxes of sexually explicit videos into the cellar and then order her to re-enact certain scenes.
The rape sessions would last for hours and she eventually stopped resisting because she knew her life was in danger if she did not co-operate, the court was told.
In the tapes, Elisabeth alleged that Fritzl had ignored her ailing newborn son Michael in 1996 and then disposed of the child's body in a stove after the boy died.
Fritzl is being asked to reply to the allegations made in each segment of the tape.
Elisabeth's testimony is so disturbing that the tape is being played in short excerpts of around an hour at a time to prevent the jurors from being traumatised.
The other highlight of the second day's proceedings was that the 73-year-old man briefly let his guard slip, dropping the A-4 blue folder with which he was covering his face. And thus the photographers got an opportunity to capture and splash across the world the image of the man widely reviled as a monster.
Much of the trial, which is expected to conclude on Thursday or Friday, is being heard in camera.
Fritzl has admitted rape, incest, false imprisonment and coercion, but has denied a charge of slavery.
He also denies murdering one of the children he fathered with Elisabeth, who was 18 when her ordeal began.
Her evidence is the backbone of the prosecution case, but the trial will also hear from expert witnesses including one who must help determine whether Fritzl let the baby die, and another who will testify about electronic locks on the doors to the cellar.
The jury will not hear from Fritzl's wife Rosemarie, 69, who has refused to give evidence.
She claimed in police interviews that she knew nothing of what her husband was doing in the soundproof bunker.
The self-confessed incest rapist is being held at St Poelten prison, next to the court, and its vice president Erich Huber-Gunstofer said his most famous incumbent was being offered psychiatric support.
"He is being offered psychiatric care to help him through the ordeal of the trial," he said.
"He can watch television because he has access to TV in the communal areas and he can also read the daily newspapers.
"He has told us that he doesn't want to exercise in the yard during the trial but he can do afterwards if he wants to.
"He has two people to protect him at all times. They don't discuss the trial with him but we are offering him therapists and he does share a cell with two other inmates.
"There is no special treatment for Josef F."