"I knew what I was doing was wrong," he is quoted as saying in an Austrian publication. "My drive to have sex with Elisabeth grew stronger and stronger. I knew Elisabeth didn't want me to do what I did to her. I knew I was hurting her... It was like an addiction."
Fritzl, 73, says he enjoyed a double life as a "normal" father upstairs -- with his wife, Rosemarie, and their six other children -- and as a sex addict in the secret basement dungeon.
"I must have been crazy to do something like that. But nevertheless I was not able to escape my double life. When I was upstairs I was totally normal. I functioned well; I made money, took care of my family and only consciously thought about downstairs when I had to run errands for my second family. But at some point, it became a matter of course for me that I led a second life in the basement of my house and that I had to take care of a second wife and our children there."
Nowhere does he mention that his so-called second wife was Elisabeth, now 42. He also does not mention that he kept her on a leash for the first nine months after he locked her up in the windowless prison.
Instead, he's reportedly described himself as a man who valued decency and good manners, and said the emphasis on discipline in Nazi times, when he grew up, might have influenced him.
"I am not the beast the media depicts me as," he's quoted as telling his lawyer Rudolf Mayer. Mayer's version of his conversation with Fritzl was published in the Austrian daily Oesterreich.
"When I went into the bunker, I brought flowers for my daughter, and books and toys for the children, and I watched adventure videos with them while Elisabeth was cooking our favorite dish. And then we all sat around the table and ate together," he reportedly told Mayer.
Fritzl said that he grew up an only child and that his mother, whom he "admired very much," threw his father out of the house when he was 4 years old.
"She was the boss at home, and I the only man in the house," Fritzl said of his mother.
Fritzl also said that Elisabeth had stopped following rules when she hit puberty and that he locked her up for her own good.
"She stayed out all night, she drank alcohol. She ran away twice and I always brought her back home."
His revelations, which were confirmed to be authentic by Mayer, are seen by many as the lawyer's strategy to prepare for an insanity defense.
Mayer told reporters in Vienna, "From a psychological point of view, there can hardly be a more absurd case and it is my job to show the man as a human being, not the horrific monster and sexual tyrant the media is portraying him to be."
The lawyer, known for taking on notorious cases, has had three in-depth conversations with Fritzl.
Meanwhile, Austrian prosecutors say it is "increasingly likely" that Fritzl, who has confessed to imprisoning and raping his daughter and fathering her seven children, will be charged with murder in the death of a newborn that died shortly after birth in the dungeon.
Gerhard Sedlacek, the prosecution spokesman, told reporters in St. Poelten today, "If it emerges that he was aware that the child was severely ill and he did nothing to get medical help, that would be a case of murder under negligence."
Fritzl was seen by a judge Friday, who has extended his detention for one more month, as is required under Austrian law. He could be kept for up to two years without being charged, provided his remand custody is regularly extended by the court.
Prosecutors expect that the investigation will take a few more months with a trial unlikely to begin before late fall.