In a gruesome scene straight out of “Psycho,” a young Brooklyn woman was found to have been living for at least a year with her mom’s skeletal remains, law-enforcement sources said.

The rotting corpse, believed to be that of Susie Rosenthal, 61, was discovered Monday under a pile of garbage bags in the Borough Park apartment she shared with her daughter, Chava Stirn, 28, according to the sources.

Police had been called to the apartment at 3 p.m. after neighbors reported a foul odor and an unexplained leak, sources said.

When cops approached Stirn, she was acting “erratically” and was taken to Maimonides Medical Center for a psych evaluation.

The corpse was found at 5 p.m., the sources said.

Neighbors told cops Rosenthal had not been seen lately.

Both mother and daughter had histories of psychological issues, sources said.

The Medical Examiner’s Office will perform an autopsy.