It’s a plot twist not even Alfred Hitchcock would think of.

The elderly Brooklyn woman found this month living with the skeletal remains of her son, possibly for as long as 20 years, is a legally blind hoarder who may not have even known he was there, NYPD sources said.

The chilling discovery of the skeleton was made Sept. 15 when a relative showed up at Rita Wolfensohn’s Midwood home to fetch her belongings and take them to her in the hospital.

In a debris-choked second-floor bedroom, sister-in-law Josette Buchman found a “completely intact” skeleton, dressed in jeans, socks and a shirt, lying on its back on a thin mattress on the floor, police sources told The Post.

“It’s like some reverse ‘Psycho’ scene,” a law enforcement source said at the time, referring to Hitchcock’s 1960 horror flick in which a son, Norman Bates, keeps his dead mother’s remains in a basement.

But investigators now believe Wolfensohn may not have known she was living with the corpse of her son. Cobwebs and garbage filled the room where the body was found — as if “a garbage truck had dumped its load” inside, police sources said.

The room reeked of rotting food, but not of ­decaying flesh, the sources said.

When police questioned the ailing woman, she spoke about her son as if he had simply moved out.

Her brother, Joseph Buch­man, and his wife, Josette, would not say where Wolfensohn — whose husband, Jesse, died in 1987 — is staying, but they were seen Saturday visiting a Long Island assisted-living facility.

Joseph told The Post he hadn’t been close to Wolfensohn for years. Another relative said he wouldn’t comment on the grisly mystery until “after the funeral.”

The widow’s Brooklyn home, a well-appointed, two-story brick house worth about $700,000, had fallen into disrepair. Last week it was empty, with mail piling up. No one answered multiple calls to the home phone.

Authorities have not officially identified the body but believe the man was Wolfensohn’s son and that he died of natural causes. They would not provide a name.

According to public rec­ords, Wolfensohn had two sons, Michael and Louis. Relatives said they had not seen Louis — who today would be 49 years old — in 20 years.

Michael died in 2003 at the age of 38, according to court documents.