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Malaysian Prime Minister Najib Razak announced that a wing piece that washed up on Reunion Island last week is from the missing Malaysia Airlines Flight 370. However, French, U.S. and Australian authorities stopped short of full confirmation, frustrating relatives with mixed messages.

A guide to the biggest aviation mystery's latest twists.

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NAJIB'S STATEMENT

Past midnight in Kuala Lumpur, Najib appeared at a news conference announcing that the metal wing piece known as the flaperon that washed ashore on the French island of Reunion in the western Indian Ocean has been confirmed to belong to Flight 370 — making it the first part of the aircraft that has been found since the plane vanished on March 8, 2014, with 239 people aboard while on the way from Kuala Lumpur to Beijing.

"We now have physical evidence that, as I announced on 24th March last year, flight MH370 tragically ended in the southern Indian Ocean," Najib said.

He said he hoped that this confirmation, "however tragic and painful, will at least bring certainty to the families and loved ones of the 239 people onboard MH370."

In a separate statement, Malaysia Airlines said the conclusion was reached in Toulouse, France, by the French agency that investigates air crashes, known as the BEA, the Malaysian investigation team, a technical representative from China — where most of the passengers are from — and the Australian Transportation Safety Bureau.

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OTHERS MORE CAUTIOUS

At a news conference in Paris, Deputy Prosecutor Serge Mackowiak didn't outright confirm that the debris belonged to Flight 370, but said there were strong indications that it was the case.

"The very strong conjectures are to be confirmed by complementary analysis that will begin tomorrow morning," Mackowiak said. "The experts are conducting their work as fast as they can in order to give complete and reliable information as quickly as possible."

The Australian government, which leads the seabed search for wreckage west of Australia, said that "based on high probability, it is MH370."

A U.S. official familiar with the investigation said the flaperon clearly is from a Boeing 777. However, a team of experts in France examining the part hadn't yet been able to find anything linking it specifically to the missing plane, the official said, speaking on condition of anonymity because there was no authorization to talk publicly about the case.

With no other 777s or flaperons known to be missing, it makes sense that the part comes from Flight 370, but the U.S. and Boeing team members are merely trying "to be precise," the official said.

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RELATIVES' ANGUISH

The mixed messages only added to the relatives' frustrations.

"Why the hell do you have one confirm and one not?" asked Christchurch, New Zealand, resident Sara Weeks, whose brother Paul Weeks was aboard the flight.

"Why not wait and get everybody on the same page so the families don't need to go through this turmoil?" she said.

In the Chinese capital, Xu Jinghong said she could not understand why Malaysian and French authorities did not make their announcement together.

"I am very angry — so angry that my hands and feet are cold," Xu said. "The announcement was made without experts from France present. I don't understand how the procedure can be like this."

One relative was pleased with the confirmation.

Irene Burrows, the 85-year-old mother of missing Australian passenger Rod Burrows, who was lost with his wife Mary, said that the announcement was a simple wish come true.

"We're quite pleased that it's been found," she said in Biloela in Australia's northeast.

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WHAT NEXT?

Analysts say the investigators will examine the metal debris with high-powered microscopes to gain insight into what caused the plane to go down. It is also not known why Flight 370 — less than an hour into the journey — turned back from its original flight path and headed in an opposite direction before turning left and flying south over the Indian Ocean for hours.

Australia has said the find will not affect its sonar search of a 120,000-square-kilometer (46,000-square-mile) expanse of seabed more than 4,000 kilometers (2,500 miles) east of Reunion Island. That search, which began in October, has covered almost half that area without finding any clues.

The Reunion Island debris would be consistent with the working theory that the jet went down in the Indian Ocean and the debris was carried by the current, which moves counterclockwise.

Malaysian officials have said the plane's movements were consistent with deliberate actions by someone on the plane, suggesting someone in the cockpit intentionally flew the aircraft off course.

Malaysia has also appealed for help from territories near Reunion to try to find more plane debris.