More than 36 hours after Flight MH370 from Kuala Lumpur to Beijing vanished, a huge search and rescue operation had found no trace of the plane or its 239 passengers.
But more ominous questions about who was on board the plane emerged on Sunday as Malaysia's Transport minister, Hishamuddin Hussein, said the identities of four passengers are now being investigated. "All four names are with me," he said, according to Reuters.
The Telegraph confirmed with China Southern, the codeshare airline which made the economy-class bookings for the men travelling under the names "Luigi Maraldi" and "Christian Kozel" that both were merely transiting in Beijing and did not require a visa.
Two separate ticketing agents at the airline confirmed that the men were booked to fly onwards from Beijing at 11.55am on March 8 to Amsterdam on a KLM flight in economy.
The two men also bought consecutively numbered tickets - 78422801116099 and 7842280116100 - suggesting that they had purchased them at the same time.
"What are the chances that one person boards a Malaysia Airlines plane on a stolen Caucasian passport?" asked one aviation expert who asked not to be named. "Maybe it is one in a thousand. Two? One in a million," he added.
After checking the names of passengers Kozel and Maraldi, the Austrian and Italian governments said that neither man was on board. Both had their passports stolen in Thailand over the last two years, and Mr Maraldi had been issued a new one according to the Italian media.
The Chinese authorities, meanwhile, said that the passport number of one of the Chinese passengers did not match the name - Zhao Qiwei - on the manifest.
Mr Hussein said the FBI was now involved in the case, and American officials are thought to be checking the passenger manifest against a list of suspected terrorists.
However, the fate of flight MH370 remains a mystery. Aviation experts said they were puzzled by the absence of debris on the waters of the Gulf of Thailand, the last known location of the plane.
An unnamed American government official told the New York Times that the Pentagon had reviewed its surveillance system that looks for flashes around the world, and saw no evidence of an explosion.
"If an aircraft disappears without any kind of distress signal, that implies that the aircraft captain or crew or both were suddenly incapacitated or that they sere so distracted in handling a problem that they could not send one," said Brad Perrett, the Asia editor of Aviation Week.
General Tan Sri Datuk Sri Rodzali Daud of the Malaysian air force also added to the mystery, saying that a military radar had seen the plane possibly turning back on its course. He said investigations were still underway and the air force was "baffled". However, Malaysia Airlines said if the plane had tried to turn around, it would have sent out an automatic signal.
09/03/14 Malcolm Moore/The Telegraph