Detectives returned yesterday to the former SoHo bodega where Etan Patz’s confessed killer says he strangled the 6-year-old.

The cops arrived at about 6 a.m. and began working on opening and examining a grate along the store’s sidewalk, near the entrance to the basement where Pedro Hernandez, 51, allegedly stuffed Etan’s body in a box on May 25, 1979.

“We took some things off the walls — scrapings — so we’ll take a look at that,” a source said.

Later, detectives went into the basement and took several photographs.