Cuffed after ma, 91, found dead

A Brooklyn man was taken into custody after cops found the body of his 91-year-old mother slashed and covered in blood in the bedroom of her Bath Beach apartment.

Petrina Masotto was found just before 1 p.m. Wednesday in the apartment she shared with a 55-year-old son in a home on 26th Ave. near Bay 43rd St.

According to sources, the son was acting erratically at the scene, telling cops he sliced the body because he was convinced it was a mannequin.

He was hauled into the 60th Precinct stationhouse for questioning, but not immediately charged. Sources said he’s undergoing a psychiatric evaluation.

The city medical examiner will conduct an autopsy to determine the cause of death.

Neighbors and family friends say Masotto and her son lived in an upstairs apartment that’s cluttered and filthy. Another 63-year-old son lives downstairs, they said. Neighbors claim the younger brother suffers from mental illness and drug abuse.

The victim and her family have lived in the home for decades, neighbors said. Her husband, a butcher, died 30 decades ago, and a third son, who served in the military, also died, neighbors said.