It's a mystery in a world with few mysteries anymore.
Theories about what happened to Malaysia Airlines Flight 370 are rampant, though many are cobbled together with dubious clues or void of facts altogether. In the absence of concrete information on where the plane is, officials haven't ruled out any possibilities.
Here are some of the theories on what happened to the Beijing-bound flight that vanished early Saturday with 239 people aboard.
The plane kept flying
Several media outlets have reported U.S. officials as saying the flight sent signals to a satellite for four hours after the aircraft vanished, raising the possibility the jet could have flown far from the current search areas.
One expert told USA TODAY the lack of warnings about a problem aboard the aircraft suggests a catastrophic failure. Steve Marks, a partner at Podhurst Orseck law firm in Miami who has represented relatives of victims in airline crashes, said the Boeing 777 should have been relaying reports of problems — if there were any. A lack of reports could mean a catastrophic failure, perhaps from the plane breaking up.
The plane's transponder, which identifies it to civilian radar systems and other nearby planes, stopped working about an hour into the flight. Experts say a massive failure knocking out its electrical systems, while unlikely, could explain the outage.
Another possibility on why the transponder stopped working is because the pilot, or a passenger, likely one with some technical knowledge, switched them off in the hope of flying undetected. Supporting this theory was a report by ABC News that two U.S. officials say that two of the plane's communication systems shut down separately shortly after the plane last communicated its position. The data reporting system, the officials said, was shut down at 1:07 a.m. as the plane was on course an hour after takeoff from Kuala Lumpur to Beijing. But the transponder, which transmits location and altitude, shut down at 1:21 a.m.
Officials haven't ruled out pilot error, though information provided by Malaysia Airlines shows the crew in the cockpit were very experienced: The flight was piloted by Capt. Zaharie Ahmad Shah, 53, of Malaysia. He has 18,365 flying hours and joined the airlines in 1981. The first officer is listed as Fariq Abdul Hamid, 27, of Malaysia. He joined the airline in 2007 and has 2,763 total flight hours.
U.S. officials told USA TODAY over the weekend they were reviewing possible terror links. Terrorism theories were fueled by information that two Iranians who boarded the flight had stolen passports. Interpol Secretary-General Ronald Noble said neither man has a criminal record. The two had bought tickets to get to Europe, where they hoped to obtain asylum.
Contributing: Associated Press