The medical examiner’s office passed the halfway mark in identifying the World Trade Center dead yesterday, as the number of victims verified by remains reached 1,401.

The bleak but encouraging milestone came a day before the one-year anniversary of the disaster that killed 2,801 and generated the largest and most prolonged forensics effort in U.S. history.

“We hope to get to 2,000 [victims identified], and when we get there, we won’t stop,” said Dr. Charles Hirsch, the city’s chief medical examiner. He spoke yesterday at his office at the morgue, where more than 50 file drawers labeled “RM DM,” for Reported Missing/Disaster Manhattan, hold information about the victims.

“After we exhaust the limits of current science, if something new or better comes along, we’ll do that. We’ll never give up,” Hirsch said.

A year later, the quest to identify those who died in the calamity carries on in a clinical sphere of groundbreaking science.

And it continues in the agony defined yesterday in the faces of three relatives who visited the huge white tent outside the office, on E. 30th St., where 16 refrigerated trailers hold the remains recovered from Ground Zero and the Fresh Kills landfill.

The three walked among the artificial flower wreaths and flickering votive candles placed near the white trucks that serve as mausoleums. The concrete-floored tent is called Memorial Park.

Mass of bodies

The forensic effort began with the surreal: a stunning number of bodies and parts of bodies brought to the medical examiner’s office in the immediate aftermath of the destruction to confirm their identities for official annals and tormented families.

At first, victims’ remains were identified by viewing a photograph of the body or through X-rays, dental records and fingerprints, and by factoring in a distinctive wedding ring or a prominent scar – techniques relying on the human eye.

NY Daily Half of Victims IDd

A total of 293 intact bodies were found, and recovery workers unearthed hundreds of parts each day. As time went on, the remains found were smaller and smaller – fragments of flesh, pieces of bone.

The identification process moved quickly to microscopes and computers as forensic specialists used DNA, and several laboratories across the nation joined the undertaking.

This month, a new DNA technique may be employed, one that can identify remains by just the tiniest snip of the genetic code.

The new technology, which relies on single nucleotide polymorphisms, or SNPs, has been used for medical purposes, but this would be its first use for forensic analysis, Hirsch said. His staff is still validating the test.

“When we started doing this, the intelligence infrastructure to do what we have to do did not exist,” Hirsch said.

The technique would be used on about 5,000 remains from which only partial DNA could be extracted because of decomposition.

The unidentified remains that will be retested – and hundreds of identified remains that survivors have not retrieved – are being methodically heat-dried so they will be preserved for the additional five months needed to complete the testing.

Experts from Kenyon International Emergency Services in Houston, which specializes in search and recovery of remains and personal effects in airline disasters, are working in a roped-off area in the white tent.

Kenyon was enlisted after the Flight 587 crash in November, when a few remains did not yield DNA. Its experts started the drying process with those and has since moved on to the World Trade Center cases.

20,000 DNA tests

By the numbers alone, the task has been formidable.

DNA extractions were done on every one of the 19,906 remains, and 4,735 of those have been identified. As many as 200 remains have been linked to a single person.

The 1,401 people identified include 45 of those aboard the hijacked planes – 33 from Flight 11, which struck the north tower, and 12 from Flight 175, which hit the south tower.

Using DNA alone, 673 people were identified. Using dental records only, 187 were identified; fingerprints only, 71; photo identification, 16; miscellaneous X-rays, 45.

There have been as many as 10 identifications a day; some days there are none. About 150 people still work around the clock in the sixth-floor lab to run the DNA samples for matches.

They will be working today, as relatives mourn in the tent outside because they still can’t go to a cemetery.