Josef Fritzl repeatedly raped his daughter in front of the children he had already fathered by her, his trial heard today.
Fritzl hid his face behind a blue file folder as a judge began the proceedings under heavy security. As expected Fritzl pleaded guilty to incest, but denied murder and enslavement.
The 73-year-old has confessed to holding his daughter in the dungeon he built beneath his home in Austria. DNA tests show he fathered her six surviving children.
One of the children died in infancy, and prosecutors charged Fritzl with his murder, saying the baby might have survived if Fritzl had arranged for medical care.
In her opening statement, prosecutor Christiane Burkheiser accused Fritzl of raping his daughter in front of the children.
Ms Burkheiser said Fritzl did not talk to his daughter during her first few years in captivity. She alleged that Fritzl once punished her by shutting off electricity to the dungeon.
Defence lawyer Rudolf Mayer appealed to the jury to be objective and not swayed by emotions. He insisted Fritzl was "not a monster."
Fritzl faces up to life imprisonment. A verdict is expected by Friday.
Fritzl's voice was weak and soft as he gave the judge his name and other personal details Monday.
Before the trial got under way his lawyer said Fritzl was nervous.
"He told me, 'I'm scared, Mr Mayer,"' he said.
Fritzl eventually removed the folder, but sat still in the dock and stared straight ahead.
Fritzl imprisoned and repeatedly raped his daughter, Elisabeth, in the cramped and windowless dungeon he built beneath the family's home in the town of Amstetten. The crime stunned the world when it came to light last April.
Security was tight around the court. Police imposed a no-fly zone above the courthouse to prevent helicopters taking aerial pictures - and to prevent prison breaks from the jail next door where Fritzl has been in pre-trial detention.
Mr Mayer welcomed the security, saying both he and Fritzl had received threats over the past year.
Three of the children grew up underground in Amstetten, never seeing the light of day. The other three were brought upstairs to be raised by Fritzl and his wife, Rosemarie, who apparently believed they had been abandoned.
The children, together with Elisabeth, initially recovered from their ordeal in a psychiatric clinic and then were moved to a secret location. Seeking refuge from reporters, they have since returned to the clinic, where security guards are on high alert.
None of the victims is expected to testify in court. Instead, the eight-member jury will see pre-recorded video testimony from both Elisabeth and one of her brothers, Harald.
In Austria, which does not have the death penalty, murder carries a maximum sentence of life imprisonment. If convicted of enslavement, Fritzl could face up to 20 years behind bars. For rape, he could get up to 15. Incest is punishable by up to one year in prison.
The conviction with the highest penalty will determine the length of the sentence.