He was 18 years old and a grocery stock clerk in SoHo when a 6-year-old boy named Etan Patz walked by on his way to his school bus stop. Pedro Hernández used a soda to lure the boy down to the basement, then strangled him, he allegedly told police, bagging and discarding the boy’s body next to a pile of trash.

Those are the details beginning to emerge about what happened 33 years ago, when a young boy’s disappearance triggered the beginning of the national missing child movement. Hernández, who was charged with the killing late Thursday, told police he cut the body up, and disposed of it in a plastic bag.

Hernández claims that he did not molest Etan before killing him.

For decades, the mystery of what happened to Etan had perplexed investigators and left many parents wondering whatever happened to the angelic-faced boy plastered on milk cartons. Etan was the first missing child to have his image appear on a milk carton.

And while now, if what Hernández told police is true, the mystery would finally be solved – but one troubling question would remain elusive.

Why’d he do it? Why’d he take the life of an innocent young boy who was walking by on his way to school?

“He was repeatedly asked why he did it, and he couldn’t give us an answer,” a source told the New York Daily News. “He said he had no idea why he did this.”

Hernández, who is charged with second-degree murder, was taken to Bellevue Hospital Friday morning and placed on suicide watch after telling authorities he was off his psychiatric medication, sources told The New York Post.

"He has been talking about killing himself," a source told the paper.

Here’s what is known about Hernández:

He’s 51, from Puerto Rico, and is married with a college age daughter. Shortly after the Etan’s death, he moved from Manhattan to Maple Shade, NJ, a suburb of Camden, to live closer to relatives.

Neighbors have told reporters he mostly kept to himself, but had a large extended family that often visited him. Hernández worked in construction until he suffered a back injury in 1993 and has since received disability payments, said New York City Police Commissioner Raymond Kelly. He said Hernández had no criminal record.

Kelly said there is no physical evidence in the case. But authorities say they have a detailed, signed confession, as well as accounts of incriminating remarks Hernández made to others.

Etan’s death seemed to have been troubling him over the years. He told a relative and others, as far back as 1981, that he had "done something bad" and killed an unnamed child in New York City, according to Kelly. Police learned that only recently, when a tipster, not a relative, pointed police to Hernández, after a search of a basement near Patz' home last month hurtled the case back into the news, Kelly said

At Hernández's New Jersey home, no one answered the door Thursday night. Neighbors said they were surprised at his arrest.

"I knew the guy. He was not a problem. His family was great people," said Dan Wollick, 71, who rents an apartment in Hernández' home. "He didn't bother anybody."

While the arrest marked only the start of what could be a complex court case, it was a stunning turn in one of the nation's most tortuous and baffling missing-children cases. Police had been aware of Hernández, as the shop was in Etan's neighborhood, but had never before eyed the married father as a suspect. Another man had long been the prime suspect, and investigators questioned yet a third man as recently as last month.

All the while, Stan and Julie Patz have stayed in same downtown Manhattan apartment, never even changing their phone number in case their vanished son tried to call.

"We can only hope," Kelly said, "that these developments bring some measure of peace to the family."

The Patzes and a lawyer for them didn't immediately return calls Thursday.

The arrest the first ever in the case was a long-sought grail for authorities, including Manhattan District Attorney Cyrus R. Vance Jr., who announced he was renewing the investigation shortly after he took office in 2010.

His office, which declined to comment Thursday, will now move on to the work of prosecuting a 33-year-old case in which nobody has ever been found. Prosecutors will likely look to amass witness statements or other evidence to support Hernández' account.

Etan vanished on May 25, 1979, in New York's busy SoHo neighborhood, which was edgier then than the swath of expensive stores it is now.

Police conducted an exhaustive search amid a crush of media attention. Thousands of fliers of the sandy-haired boy with the toothy grin were plastered around the city. Buildings were canvassed and hundreds of people interviewed.

The disappearance ushered in an era of anxiety about leaving children unsupervised, and President Ronald Reagan designated the anniversary as National Missing Children's Day in 1983.

Detectives are often inundated with hoaxes, false leads and possible sightings around the anniversary. But Kelly said they had probable cause to believe Hernández's story was true, because of specific details he gave to police.

Hernández, who had worked at the convenience store for about a month and lived nearby, wasn't questioned at the outset, Kelly said. Days after Etan vanished, Hernández left that job and moved to New Jersey.

Police took Hernández into custody Wednesday night, and after several hours of questioning, he provided a signed confession, Kelly said.

"He was remorseful, and I think the detectives thought that it was a feeling of relief on his part," the commissioner said.

Earlier leads had arisen and stalled, at one point taking investigators as far as Israel to track reported sightings of Etan.

For most of the past decade, the investigation focused on José Ramos, a convicted child molester now in prison in Pennsylvania. He had been dating Etan's baby sitter.

A civil judge found him to be responsible for the boy's disappearance and presumed death, largely because he refused to answer some questions under oath, but he was never criminally charged. He might be able to get the civil judgment reviewed now.

A few weeks ago, investigators excavated a basement down the street from the Patz apartment but found no human remains. They questioned a handyman who had a workspace in the cellar in 1979. But he was not named as a suspect and denied any involvement in the boy's disappearance.

Finally, on Thursday, police told Patz' parents they had honed in on Hernández.

"Mr. Patz was taken aback, a little surprised, and I would say overwhelmed, to a degree," Lt. Christopher Zimmerman said. " ... He was a little surprised, but I think after everything Mr. Patz has gone through, he handled it very well."

Gilbert López, who identified himself as a brother-in-law of Hernández, told the Wall Street Journal the suspect is one of about 12 children. Their mother died about seven years ago, and with her death, the family's large Thanksgiving gatherings came to an end.

López, 45, said he was shaken by the news of his brother-in-law's arrest.

"A good family man. Quiet. Always nice," Lopez said. "I can't believe all this is happening."

Contains material from The Associated Press. 

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