U.S. law enforcement officials began their own fresh background checks on the passengers and crew of
Thus far they have turned up no evidence of any "traditional" jihadist terror link to the plane's disappearance. But they remain intrigued over whether the pilot or copilot diverted the jumbo jet, and whether one or more of the passengers took control of the cockpit or forced the crew to turn the flight westward from its Kuala Lumpur-to-Beijing course.
"This is feeling like kind of a failed hijacking," said one federal law enforcement official, speaking anonymously because the investigation was still underway.
He said U.S. authorities theorize that once the plane was diverted toward the Indian Ocean, it was flown erratically at high altitudes in an attempt to depressurize the cabin and render the passengers unconscious. "That could have neutralized any threat from them to take the plane back," he said.
The source said the U.S. was briefed by Malaysian authorities, who said they had begun searching the homes of the pilot and copilot Saturday, something he said the U.S. would have done immediately after the plane vanished a week ago.
There was little to suggest erratic behavior on the part of the pilot or copilot, though each had some personal quirks — the pilot had a flight simulator at home and the copilot had invited women into the cockpit in the past, the source said.
Malaysian law enforcement officials likewise have told their U.S. counterparts that they have no reason to suspect the flight crew, he added.
The U.S. source also said there still was no sign of terrorist radicalization by two Iranian passengers who boarded the flight from to Beijing bearing stolen passports.
At the National Counterterrorism Center, meanwhile, analysts have checked the names of each passenger and crew member against the most sophisticated databases in the U.S. intelligence repository, according to a U.S. counter-intelligence official speaking confidentially. But that search has turned up nothing, he said.
"We still have not identified any clear nexus to terrorism," the official said.