Now even French investigators are convinced: The airplane debris found on Reunion Island in July belonged to vanished Malaysia Airlines Flight 370, a top French prosecutor said Thursday.

Investigators learned Thursday that a series of numbers found inside the plane flaperon matches with records, held by a Spanish company that manufactured portions of the component, linking the debris to MH370, the office of Paris Prosecutor Francois Molins said.

“Consequently, it is possible today to affirm with certainty that the flaperon discovered at the Reunion Island on July 29, 2015 is that of MH370,” the office said.

The announcement slices the last thread of public reservation that Molins’ office had about whether the debris was linked to the Boeing 777 that disappeared with 239 people aboard in March 2014.

The Malaysian Prime Minister said weeks ago that the debris, found in July on the shores of the French island in the Indian Ocean, clearly was from MH370. French investigators, however, had said that further testing was needed to say that with ironclad confidence. Some passengers’ relatives agreed, saying they wanted more proof.

French investigators now believe they have it. France, which already had launched a criminal probe into the disappearance because four French nationals were aboard, sent the debris to a specialized laboratory in Toulouse last month.

The search for MH370
The search for MH370

Molins’ office said that experts using an endoscope found three series of numbers inside the flaperon. It appeared, the office said, that the numbers could correspond to a Boeing subcontractor, Airbus Defense and Space in Seville, Spain.

On Thursday, investigators went to Seville and formally linked “one of the three (series of numbers) collected inside the flaperon to the serial number of the Boeing 777 of flight MH370,” Molins’ office said.

The mystery of MH370

In the early hours of March 8, 2014, MH370 took off from Kuala Lumpur International Airport in Malaysia en route to Beijing, with 239 passengers and crew on board.

At 1:19 a.m., as the Boeing 777-200ER was flying over the South China Sea, Malaysian air traffic controllers radioed the crew to contact controllers in Ho Chi Minh City for the onward flight through Vietnamese airspace.

The crew’s acknowledgment of the request was the last thing ever heard from MH370: “Good night Malaysian three-seven-zero.”

Shortly afterward, air traffic controllers in Malaysia lost contact with the plane somewhere over the sea between Malaysia and Vietnam.

The aircraft’s transponder, which identifies the plane and relays details like altitude and speed to controllers, stopped transmitting. MH370 seemingly disappeared without a trace.

Malaysian authorities revealed later that military radar had tracked the plane as it turned back to the west and flew across the Malaysian Peninsula, up the Strait of Malacca, before flying out of radar range at 2:14 a.m. and vanishing once again.

As reported by CNN