London, May 12 (ANI): Sex beast Josef Fritzl's wife Rosemarie is to be questioned again by police to determine whether she knew about his secret life in the cellar.

Detectives are to conduct a forensic search of the upper floors of the "house of horrors" where Fritzl, 73, lived with his 68-year-old wife, while their daughter Elisabeth, whom he raped for 24 years and fathered 7 kids with, was locked in the basement.

"We think Fritzl acted alone but cannot exclude the possibility that someone else was aware of what was going on downstairs," Times Online quoted Frank Polzer, the chief investigator, as saying.

Her claim to have known nothing about her daughter's ordeal has raised eyebrows, as has the collective blindness of Amstetten, a town 75 miles west of Vienna, to what was unfolding beneath one of its main streets.

However, he said that Rosemarie would not be held a suspect, saying: "What woman would stay silent if she knew her husband had seven children with his daughter and was holding her prisoner in the cellar?"

Still, the cops want to question Rosemarie and other relatives to avoid any kind of complications.

While three of Elisabeth's kids were caged with her, the brute duped Rosemarie into believing that the other three children were dumped by "runaway" Elisabeth, and were later adopted by Rosemarie.

According to neighbours Rosemarie was devoted to the three children she adopted, but many people still were doubtful of her involvement. "I don't think anyone around here knew anything. But naturally what was happening with Frau Fritzl is a different and difficult question. How someone can live with someone like that and not see anything is hard to understand." Mirror quoted next door cafe owner Gunther Pramrieter, 38, as saying. Many people in the neighbourhood have seen Fritzls buying carloads of food but thought it was meant for the kids upstairs.

According to psychologists, might be subconsciously pretending to know nothing of her husband's secret double life.

Rosemarie is now suffering from a severe heart problem. (ANI)