News that the New York Police Department has a man in custody who has implicated himself in the 1979 disappearance of Etan Patz raises the tantalizing possibility that this case might finally be solved.

It's the latest in a long series of twists and turns as investigators try to unravel a mystery that has stymied them for 33 years: What happened to Etan Patz?

Commissioner Ray Kelly of the New York Police Department says investigators will divulge more details later Thursday.

In the meantime, the man's statements raise hopes that investigators might learn -- at last -- of what happened to the six-year-old boy who disappeared on his way to the school bus stop 33 years ago.

There have been a series of such leads over the years in the case, which changed the nation's attitudes toward children's safety and helped launch the missing children's movement. One of those leads raised hopes last month of a break in the case -- but it did not pan out.

First there was the drifter living in a drainage tunnel with pictures of boys who looked eerily similar to Etan. A rash of false leads that took investigators as far afield as Israel chasing look-alikes. Then, more recently, a cadaver dog picking up the scent of human remains in a basement near Etan's home, leading a team of investigators to tear it up.

Each time, the result has been the same: sometimes a few answers, often more questions, and rarely anything resembling the full truth for Etan's parents, Stan and Julie Patz.

The family has endured years of crank calls and far-fetched theories on the home telephone number they never changed in hope Etan might some day try to call.

"They exacted the biggest emotional cost, riding Stan and Julie on a steep vertical incline up the tracks, to plunge straight back down to hell every time," journalist Lisa Cohen writes in her definitive account of the case, "After Etan: The Missing Child Case That Held America Captive."

Such dramatic ups and downs have long been part and parcel of the investigation into Etan's disappearance.

In the days and weeks after he went missing in May, 1979, police, the family and neighborhood volunteers worked tirelessly tracking down leads, according to Cohen.

In the two weeks following Etan's disappearance, police put in more than 4,000 hours on the case, interviewing some 500 people, Cohen writes in her book.

Police cruisers swarmed the neighborhood as volunteers plastered the area with 10,000 posters, according to Cohen's account.

Then came the first letdown.

The police officers who'd camped in the Patz home, answering phones and dispatching detectives to follow up on possible leads, packed up and left, the emergency phase of the response over.

In their place, they left a legal pad next to the phone and instructions to log each call. What had been a stream of calls slowed to a trickle, but kept coming, with their stories of boys matching Etan's description seen in places near and far.

None panned out.

Three years later, in 1982, the roller-coaster would start its climb again with reports that a man, Juan Antonio Ramos, had swiped a boy's book bag and tried to lure him and another boy into the drainage tunnel where he was living.

Police found photos of young boys among the man's possessions, and took them to Etan's parents to see if their son was one of them.

"Almost three years into their ordeal, the half-formed scab covering their private life and private pain was being picked off yet again to ooze fresh blood," Cohen wrote in her book. "They greeted the news with the now familiar mix of trepidation tinged with the faint hope, one that could never be discounted, that new exposure could yield new information."

The case didn't pan out, at least initially, and Ramos vanished.

Interest moved on to other reports, Cohen wrote in her book: A photo in Israel, another in Massachusetts. A cab driver who said he picked up the boy the morning of his disappearance.

Like the other leads, nothing came of them.

In 1988, the cycle began turning again. Investigators turned their attention back to Ramos after locating him in a Pennsylvania prison -- where he was serving time on a molestation conviction.

They brought Ramos back to New York for questioning, and got a bombshell, Cohen writes.