Investigators are poring over decades-old sanitation records and garbage truck routes, weighing whether to undertake a massive search for Etan Patz's remains in city landfills, a law enforcement source and city officials said Saturday.

That daunting prospect materialized suddenly, after a New Jersey man confessed last week to killing Etan in 1979. Police say he told them he stuffed the 6-year-old boy's body in a trash bag and dumped it on a nearby SoHo sidewalk.

The chances of finding the remains today are remote, authorities and at least one expert say.

Trash delivered to city landfills 33 years ago has been buried under mountains of waste, and a massive incinerator in use at the time could have destroyed the evidence.

Despite their low expectations, investigators are delving deep into the city's sanitation history in hopes of tracking the trash bag "from the moment a sanitation worker might have picked it up to the moment it reached a waste facility," said a law enforcement source with knowledge of the investigation.

"Everything is being looked at," the source said. "Records. Maps. Routes. Everything."

Investigators say the man accused of Etan's murder, Pedro Hernandez, 51, of Maple Shade, N.J., told them he left the bag containing Etan's remains in front of 113 Thompson St. -- a block and a half from the SoHo bodega where he allegedly strangled the boy.

The unemployed father of three, who allegedly told detectives he lured Etan into the basement with the promise of a soda, was arraigned Friday on a second-degree murder charge. Hernandez's lawyer, Harvey Fishbein, has said his client suffers from schizophrenia and bipolar disorder, and has a history of hallucinations.

If the former bodega stock clerk's story is true, the garbage bag would have likely been taken to one of three now-shuttered waste facilities: the Fountain Avenue Landfill in Brooklyn; the Fresh Kills Landfill in Staten Island; or the Gansevoort Incinerator in Manhattan, officials said.

"Where refuse from that area was dumped and whether it was handled by DSNY or privates is part of that [Patz] investigation," said Vito Turso, spokesman for the New York City Sanitation Department, who confirmed his agency is cooperating with police.

In 1979, Fresh Kills and Fountain Avenue were accepting municipal and commercial waste. But Turso said the nearby Gansevoort Incinerator was also active.

Landfills around the country have been scoured for murder victims before, with mixed results. But those searches are usually conducted within weeks or months of the crime, aided by cadaver dogs.

The passage of time and amount of garbage packed into Fresh Kills and Fountain Avenue make finding Etan's remains highly unlikely, said former NYPD officer Eugene O'Donnell, a professor at John Jay College of Criminal Justice.

"This is well beyond a needle in a haystack," he said. "It seems impossible to believe they would be able to find that bag."

George Kramer, 72, who lived in SoHo when Patz vanished, said locals always knew their trash could hold the key to solving the missing person case — but assumed sanitation workers were paying close attention to their hauls.

"If one of them picked up a bag with a strange shape that weighed so much, how could they not stop and take a look?" asked Kramer, who still lives in the neighborhood.

"If they had, knowing what we know now, maybe Etan would have been found that weekend," he said. "Now, they would have to dig up a couple thousand tons of trash in landfills to even get close. It's impossible."

As police continued their investigation on Saturday, visitors left flowers and candles outside the former bodega's location at 448 W. Broadway where Hernandez said he strangled Etan.

Etan's parents, who still live two blocks from the bus stop where Etan vanished, posted a note on their door saying they weren't discussing the case.

"The answer to all your questions is 'no comment,' the note said. "Please stop ringing our bell and calling our phone for interviews — Stan Patz, 3E."

With Igor Kossov

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