The theory that the missing Malaysia Airlines jet was hijacked and diverted -- possibly to Indonesia -- to be used as a "weapon" in a future attack gained traction Monday from the chairman of the House Homeland Security Committee.
Rep. Michael McCaul, R-Texas, told Fox News that the two most plausible scenarios at this stage are that Flight 370 ran out of fuel and crashed into the Indian Ocean, or that the plane has already landed "somewhere in southeast Asia" as part of a terror plot.
"It could have landed somewhere, filled with explosives and then sent somewhere else to cause some great damage, and I think we have to look at all possibilities right now," McCaul told Fox News.
The theory that the missing plane is being housed in a secret location is one of dozens that have emerged since the Boeing 777 disappeared. But with the international investigation now focusing on sabotage and foul play, the possibility of a terror link remains on the table.
"We do have to use ... imagination. This is one of the most mysterious flights probably since Amelia Earhart's disappearance," McCaul said, while acknowledging "no one really knows the truth behind the motivation."
McCaul also confirmed that FBI agents were on the ground on Sunday, and that the computer hard drives of the pilot and co-pilot are currently being reviewed. McCaul said that should lead to new information.
Meanwhile, McCaul and other officials are calling on Malaysian authorities to give FBI investigators greater access to help with the probe.
New York Republican Rep. Peter King complained on Sunday that the Malaysian government was "not cooperating."
Much of the frustration is being directed toward Malaysian officials, who apparently waited nine days after Malaysia Airlines Flight 370 disappeared March 8 over the Indian Ocean to search the pilot and co-pilots' home -- though Malaysian officials are now challenging that claim.
King said the pilots should have been the focus from the start. King told ABC's "This Week" that more intelligence agencies need to be hands-on in the probe. He wants the NTSB, the FBI, the Federal Aviation Administration and the international police agency Interpol to be more involved in the investigation, which includes a search over 5 million square miles for the craft and its "black boxes," which hold key data to help solve the mystery.
Since last week, the search for the missing Malaysian jet has pushed deep into the northern and southern hemispheres as Australia on Monday scoured the southern Indian Ocean and China offered 21 satellites to respond to Malaysia's call for help in the unprecedented hunt.
Malaysian authorities say the jet carrying 239 people was intentionally diverted from its flight path during an overnight flight from Kuala Lumpur to Beijing on March 8 and flew off-course for several hours. Suspicion has fallen on the pilots, although Malaysian officials have said they are looking into everyone aboard the flight.
Malaysian police confiscated a flight simulator from the pilot's home on Saturday and also visited the home of the co-pilot in what Malaysian police chief Khalid Abu Bakar initially said was the first police visits to those homes. But the government -- which has come under criticism abroad for missteps and foot-dragging in their release of information -- issued a statement Monday contradicting that account by saying police first visited the pilots' homes as early as March 9, the day after the flight.
Investigators haven't ruled out hijacking, sabotage, pilot suicide or mass murder, and they are checking the backgrounds of all 227 passengers and 12 crew members, as well as the ground crew, to see if links to terrorists, personal problems or psychological issues could be factors.
For now, though, Malaysian Defense Minister Hishammuddin Hussein said finding the plane was still the main focus, and he did not rule out finding it intact.
Fox News' Catherine Herridge and The Associated Press contributed to this report.