A Queens man found what appeared to be a bag of human bones in his basement Saturday and police believe it could be the remains of his son’s girlfriend —  who was last seen four months ago, according to cops and sources.

The grisly find happened at 217-05 138th Ave. in Laurelton around 5:45 p.m., police said.

A 65-year-old man who owns the home called police after he found the decomposed remains of a person in a plastic bag under boards of plywood while cleaning his basement, according to sources.

The man told police he had an idea of who the remains belonged to, and his 30-year-old son was immediately taken into custody, sources said.

Police confirmed a 30-year-old man was in custody but didn’t confirm the relationship with the homeowner.

Detectives believed the body was “possibly” the person of interest’s girlfriend, who had been missing, according to sources. 

The coroner was examining the remains to determine the cause of death, according to officials.