NEW YORK (AP) — In a potential break in one of the nation’s most baffling missing-children cases, a former convenience-store employee has told police that he suffocated 6-year-old Etan Patz in 1979 and left the boy’s body in a box in an alley, law enforcement officials said Thursday.

If Pedro Hernandez’s story checks out, it could solve the 33-year-old mystery of what happened to Etan, whose disappearance on his way to school helped give rise to the nation’s missing-children movement and made him one of the first abducted youngsters to be pictured on a milk carton.

After decades of dead-end leads and phony confessions, investigators warned they are still trying to confirm Hernandez’s account and have little to go on other than his word. No body has been found. No charges have been filed.

“Let me caution you that there’s still a lot of investigating to do,” Mayor Michael Bloomberg said.

Hernandez, who is believed to be in his mid-60s, worked at a store in the neighborhood where Patz lived, authorities said.

He told investigators that he suffocated the boy, then put the body in a box, walked down a Manhattan street and dumped the box in an alley, according to a law enforcement official who was not authorised to discuss the investigation and spoke to The Associated Press on condition of anonymity.

The development came a day before the anniversary of Etan’s disappearance, when detectives are typically barraged with hoaxes, false leads and possible sightings.

Hernandez, who moved to New Jersey shortly after the boy vanished, was picked up there late Wednesday and was being questioned Thursday at the Manhattan district attorney’s office.

He had been tied to the case in the past, and investigators recently received a phone call with a new tip, according to the law enforcement official. The official gave no details on the tip.

Neighbors in Maple Shade, N.J., said Hernandez lived with his wife and a daughter who attends college.

“I can’t believe something like that,” said Dan Wollick, a neighbor in the same building. “This guy, he doesn’t seem that way.”

Sandy-haired Etan vanished without a trace on May 25, 1979, while walking alone to his bus stop for the first time, two blocks from his home in New York’s busy SoHo neighborhood, which was a working-class part of the city back then but is now a chic area of boutiques and galleries.

Etan’s disappearance ushered in an era of anxiety about leaving children unsupervised. Police conducted an exhaustive search. Thousands of fliers were plastered around the city, buildings canvassed, hundreds of people interviewed.

Etan’s parents, Stan and Julie Patz, were reluctant to move or even change their phone number in case their son tried to reach out. They still live in the same apartment.

They did not return a call for comment.

“I hope this is the end of it,” said Roz Radd, who lives a couple of blocks from the Patz family’s home and knows Etan’s mother casually from walking dogs in the neighbourhood. “There’s going to be hopefully closure to her, to know what happened to her son.”

The FBI, which has been part of the investigation, had no comment. In a statement, New York Police Commissioner Raymond Kelly said only that a man had “made statements to NYPD detectives implicating himself in the disappearance and death of Etan Patz.”

Prosecutors would most likely look for evidence to corroborate his statement before bringing charges. They would also presumably try to gauge his credibility.

“Anybody can come forward and say, `I did it,’ but you need to be able to prove that it’s the truth,” said Pace Law School professor Bennett L. Gershman, a former prosecutor in Manhattan.

DNA or other physical evidence might not be available, but investigators could try to find witnesses who could connect Hernandez to the crime. They could also try to discern whether he knows details about the disappearance that weren’t made public, or said revealing things about the case to others.

Since the early 1980s, the investigation has ebbed and flowed. It included a trip to Israel after reported sightings there of the boy, and in the past decade focused on Jose Ramos, a convicted child molester now in prison in Pennsylvania, who had been dating Etan’s baby sitter. In 2000, authorities dug up Ramos’ former basement in lower Manhattan, but nothing turned up.

Stan Patz had his son legally declared dead in 2001 so he could sue Ramos, who denied harming the boy. A judge in 2004 ruled Ramos responsible for Etan’s death after Ramos refused to answer questions in the lawsuit. But Ramos was never charged with a crime.

In 2010, District Attorney Cyrus R. Vance Jr. announced he was reinvestigating the case.

A few weeks ago, investigators excavated a basement down the street from the Patz apartment for signs of Etan but found no human remains. Investigators questioned 75-year-old Othniel Miller, who in 1979 had a workspace in the cellar. But he was not named as a suspect.

Miller’s lawyer, Michael Farkas, said Thursday: “Mr. Miller is relieved by these developments, as he was not involved in any way with Etan Patz’s disappearance.”