London, June 4: Austrian incest dad Josef Fritzl, who imprisoned his daughter in a cellar for 24 years, acted alone, say police officials.

The 73-year-old beast fathered daughter Elisabeth's seven children before freeing her in April this year.

Ex-lodgers at the Fritzl home in Amstetten, Austria, suggested others may have been aware of the dungeon.

But, on June 3, prosecutor Gerhard Sedlacek said that the theory was unlikely, reports the Mirror.

If anything had happened to Fritzl, the family in the cellar would not have been able to escape and would have died.

Three of the children - Kerstin, 19, Stefan, 18 and Felix, five - lived all their lives in the cellar.

Fritzl is under arrest while his family are under guard in psychiatric care. (ANI)