INCEST monster Josef Fritzl was visited in prison by a man claiming to be his son.
A justice official revealed that the man went to see Fritzl, 88, in Stein Prison in Krems, Austria, and told him: "I think you're my dad."
The visit was first revealed by Austrian newspaper Kronen Zeitung which said Fritzl once had an "affair" with the man's mother.
A justice official speaking on condition of anonymity confirmed the visit.
They told The Sun: "Yes, this person exists. There has been a visit. That claim in the Kronen Zeitung is accurate.
"It is possible that he is his son, who knows?"
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Neither the man or his mum have been identified - and it's currently not known if Fritzl will be asked to undergo a DNA paternity test.
He reportedly said at the same time: "A DNA test will confirm if I have another son.
"If that is true, then the public must never know his identity."
The justice source explained: "We'll have to wait and see what happens next."
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Fritzl was sentenced to life in prison in 2009 after locking his daughter, Elisabeth, in the basement of his home in Amstetten, Austria, for 24 years and fathering seven children with her.
One, who died at birth with breathing difficulties, was heartlessly tossed in a furnace by Fritzl.
Three were brought up in the basement with their mum and three others were brought up as foundlings by sick Fritzl and his wife.
Now, after 15 years behind bars, the perverted pensioner is eligible for parole this year.
Under local laws, inmates deemed ready for parole can be freed depending on their conduct and mental and physical condition.
Fritzl, who has asked to be released, is set to have his case reviewed by justice and prison officials.
Adelheid Kastner, one of Austria's most renowned psychiatrists, said Fritzl was no longer a threat to society.
She said Fritzl, who has Alzheimer's disease, would be incapable of carrying out any crimes.
And lawyer Astrid Wagner, who last year published a book based on a series of letters he sent her, revealed that Fritzl could be relocated to a regular public care home.
Wagner, who visits Fritzl regularly, told The Sun: "I personally see a chance for a release.
"He fulfils all the criteria. It is of course within the bounds of possibility that his new accommodation could be a public institution for elderly people."
She added: "This man is almost 90-years-old and his mental condition is deteriorating. He is in need of support and care.
"It is possible to normally communicate with him most of the time.
"However, there are these odd lapses. One day he told me how happy he was about his daughter's marriage to Boris Becker.
"The next time I saw him he told me they had broken up."
Wagner said Fritzl also boasted about being part of a television show.
"There are these paranoid thoughts but this has to do with his age," she said.
Last year, she described him as "only human, not a beast".
Wagner said a three-member panel of judges will decide whether he can be released.
In his trial in 2009, Fritzl plead guilty to rape, false imprisonment, manslaughter by negligence and incest.
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Seven years ago, Fritzl changed his name to Mayrhoff in an alleged attempt to evade physical attacks by other inmates.
Elisabeth Fritzl has since changed her name and has received support from the authorities in protecting her identity and the wellbeing of her children.