A Brooklyn man killed his mother and stabbed his father during an argument over shoes, a police source said Sunday.

Oscar Rodriguez Jr., 55, is suspected of flying into a fit of rage and plunging a knife into his 77-year-old mother, Maria Rodriguez, when she tried to break up a fight between the two men at the family’s Bushwick apartment late Friday or early Saturday, a high-ranking source said.

Rodriguez Jr. had just returned home barefoot when his father, Oscar Rodriguez, questioned why he wasn’t wearing any footwear, the source said.

The enraged son allegedly knifed his dad in the arms and chest, then fatally stabbed his mother and fled, according to the source.

The elderly couple lay covered in blood until their son-in-law, Artelio Reyes, 63, discovered them Saturday evening inside the apartment at Garden and Noll streets, the source said. Reyes had climbed through a window at the home after becoming worried that he couldn’t reach them by phone, the source said.

The father, who suffered serious injuries, told police his son attacked them, the source said.

Police arrested Rodriguez Jr. after receiving an unrelated 911 call about a violent and emotionally disturbed person wandering around the area Saturday. Cops didn’t know at the time that Rodriguez Jr. was linked to the murder and took him to the psychiatric unit of Woodhull Hospital.

A neighbor said Rodriguez Jr. had clashed with his mom in the past.

“They did not get along,” said the neighbor, who identified herself only as Sarah. “I am shocked she’s gone. [It’s] horrible.”

Rodriguez Jr., who is still in the psych unit, had not been charged with a crime Sunday, the police source said. The hospital is not cooperating, so cops have yet to speak with him, the source said.

Detectives are trying to get a search warrant to retrieve the suspected bloody pajamas that Rodriguez was wearing at the time of the crime and when he was picked up, the source said.

A hospital spokesman told The Post he was looking into the matter.

Additional reporting by C.J. Sullivan