The Times of London reported Sunday that investigators believe Fritzl, 73, may have been involved in the slaying of Anna Neumayr, a 17-year-old girl found dead in a cornfield near her home in southern Austria in 1966.

"We will investigate whether there is anything to indicate that Josef Fritzl was near the scene at the time," a police spokesperson said.

The newspaper reported that less than a year after the 1967 murder, Fritzl was convicted of rape and attempted rape and served 18 months in prison.

Fritzl has confessed to having fathered seven children by his daughter, Elisabeth, now 42, after locking her in a home-made dungeon under the family home in Amstetten in 1984.

He is also facing manslaughter charges because one of the children he fathered with his daughter died shortly after birth, and Fritzl allegedly threw the dead baby's body into a heating oven.