NEW YORK (CBSNewYork/AP) — A piece of aircraft wreckage that was found wedged between two buildings near the World Trade Center site came from the wing of a plane, police said Monday.

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Boeing Co. confirmed the rusted metal part from a Boeing 767 is a trailing edge flap support structure, NYPD spokesman Paul Browne said. It helps secure wing flaps that aid in regulating plane speed.

The wreckage had a clearly visible Boeing identification number and investigators initially thought it was part of the landing gear because both pieces have similar hydraulics.

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“It is believed to be from one of the two aircraft destroyed on Sept. 11, 2001, but it could not be determined which one,” Browne said. The American Airlines and United Airlines planes hijacked by Islamic extremists on 9/11 were Boeing 767s.

As CBS 2’s Steve Langford reported, the Boeing 767 part was found in a dirty alley about three blocks from the World Trade Center.

Workers found the mangled piece of metal wedged between 51 Park Place and 50 Murray St., on Wednesday in a gap just 18 inches wide.

“It certainly is possible that it was wedged down there and went directly into the alley. Depends on the angle with which it hit,” said NYPD Commissioner Ray Kelly.

“It’s shocking to me,” said Newark resident Mirza Katideen. “I would never imagine 11 years later, they’d find something like that.”

51 Park Landing Gear (NYPD)

51 Park Landing Gear (NYPD)

The Medical Examiner’s Office plans to search for Sept. 11 human remains in the alley where the piece was found.

The chief medical examiner’s spokeswoman, Ellen Borakove, said the area first will be tested as part of a standard health and safety evaluation for possible toxicity. Sifting for human remains is to begin Tuesday morning and should be finished by Wednesday, police said.

Of the nearly 3,000 victims, about 1,000 families have never recovered any traces of their loved ones.

“We’re outraged, the families. I mean, it’s upsetting,” said retired FDNY deputy chief Jim Riches, whose firefighter son died on 9/11.

Riches has demanded federal authorities be brought in to search for the remains of so many who vanished on Sept. 11.

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“There’s a thousand families who’ve never recovered anything. They’ve had no funeral, they have no cemetery to go to. We feel that you need a full, comprehensive search of Lower Manhattan now to make sure there are no body parts laying around all over the place and we get another surprise 10 years from now,” Riches told Langford.

The NYPD has declared the alley a crime scene where nothing may be disturbed until the Medical Examiner’s Office completes its work.

Once the medical examiner is finished, the NYPD Emergency Service Unit will remove the flap support structure from behind the building, Browne said. He said the part could be removed from the alley on Wednesday.

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The twisted metal part has cables and levers on it and is about 5 feet high, 17 inches wide and 4 feet long, Kelly said.

The hidden alley where the part was found is behind the site of a proposed Islamic community center that has spurred nationwide controversy.

Police had also been questioning if someone placed the part there on purpose since it appears there was also a rope wrapped around it. However, detectives learned one of the officers who had first responded to the scene apparently used rope that he found on the ground nearby to wrap it around the part in order to move it to look for its serial number and other identifiers, Browne said in a statement.

As authorities continue to investigate the alley, workers at nearby One World Trade Center were set to raise the final two sections of the 408-foot spire that will sit on top of the building.

The work was expected to be done Monday, but the weather did not cooperate.

When the last pieces of its spire rise to the roof, the 104-floor skyscraper will be just feet from becoming the highest in the Western Hemisphere.

Installation of the 800-ton spire began in December after 18 pieces were shipped from Canada and New Jersey.

The spire will serve as a world-class broadcast antenna and provide public transmission services for television and radio broadcast channels that were destroyed on Sept. 11, 2001, along with the trade center towers.

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