Police have arrested a 51-year-old New Jersey man who earlier implicated himself in the 1979 disappearance of Etan Patz, a case that baffled New York City for decades, sparked a nationwide campaign on behalf of missing children and helped make Etan the first child whose picture was posted on the side of a milk carton.

New York police commissioner Ray Kelly said at a press conference late Thursday that Pedro Hernandez used a can of soda to lure the 6-year-old into the small grocery where he worked, then strangled him to death. Kelly said police began to close in on Hernandez thanks to an unnamed tipster who came forward following press coverage of the excavation of a basement nearby in a renewed search for clues to Etan’s disappearance.

Prosecutors charged Hernandez with second-degree murder.

(MORE: Etan Patz Case: With No Clues to Boy’s Disappearance, Search Ends)

Kelly could not explain why Hernandez, who was a person the NYPD knew about, was never questioned in the case. “I can’t tell you why 33 years ago he wasn’t questioned,” Kelly said. “Other people in the bodega were questioned.”

The abduction took place almost 33 years ago to the day: Friday, May 25, 1979, around 8:30 a.m. — the first day Etan was allowed to catch his school bus unsupervised. His home sat about a block away from the stop. Police believe that Hernandez had not had prior contact with Etan and that he had only worked in the grocery for about a month. After Etan’s disappearance, Hernandez quit and moved to Camden, N.J., just outside Philadelphia, where he has many family members.

Hernandez was picked up by police in Camden on Wednesday and taken to New York for questioning by authorities. In a taped interview that extended for more than three hours, police described the man as nonadversarial about being taken in for questioning. “He was remorseful, and I think the detectives thought that it was a feeling of relief on his part,” said Kelly.

Hernandez told police that after killing Etan, he stuffed his body into a bag, then disposed of it in the trash, which was most likely picked up by city sanitation workers. Hernandez was not subjected to a polygraph test, and without a body or other evidence, prosecutors must build a case based on Hernandez’s confession and the statement of the tipster. But police are confident in what they have. “Detectives believe in the validity of the statements of Mr. Hernandez,” Kelly said.

(MORE: Etan Patz: FBI Searches New York Basement for Sign of First Missing ‘Milk Carton’ Boy)

Etan disappeared while walking from his home in the SoHo district, then a working-class neighborhood. His parents Stan and Julie Patz exhausted themselves looking for their son and turned the search into a campaign for the cause of missing children nationwide. By 1983, Stan Patz, a professional photographer, had distributed his son’s pictures virtually everywhere, and the photo was used by the National Center for Missing & Exploited Children for its milk-carton campaign. Etan’s was the first of many children’s pictures to be placed on the backs of the cartons.

With thousands of posters placed around the city and massive media attention brought to the case, the Patzes remained in the same apartment in hopes that Etan would try to find his way home. Although hundreds of people were interviewed, few turned up as persons of interest. One of them, Jose Ramos, who babysat Etan at the time, has been a main suspect in the case, but he was never arrested and has always denied harming the boy. Ramos, a convicted child molester who is serving time in Pennsylvania on an unrelated charge, was found by a judge to be responsible for the boy’s death and was ordered to pay Etan’s parents $2 million. To date, he has not given them any money.

The Patzes had their son declared legally dead in 2001.

Another person of interest, Othneil Miller, 75, was mentioned earlier this year, as authorities excavated a SoHo building in April that had once housed his small shop. Miller is said to have given Etan dollar bills for performing small jobs. The basement shop sits along the route that Etan would have normally taken to his school-bus stop. The building — now part of a far different SoHo, dotted with posh restaurants and expensive boutiques — was searched as part of a reopening of the case announced in 2010. Miller, who was never implicated in the case, has always maintained his innocence, and the search failed to turn up any clues in Etan’s disappearance.

The search had no connection to Hernandez’s questioning; Kelly told reporters on Thursday that police had acted on a tip. Investigators are trying to determine what, if anything, Hernandez has told family members in the years since Etan vanished.

“I just cannot imagine what they have gone through,” New York Mayor Michael Bloomberg told reporters earlier Thursday, referring to Etan’s relatives. “And I certainly hope we are one step closer to bringing them some measure of relief.”

MORE: Did Etan Patz Mark the End of Carefree Parenting?

— With reporting by Nick Carbone and Tim Morrison