SYDNEY — From a hijacking to an alien abduction, countless theories have arisen about the fate of the Malaysian airliner that disappeared nearly two years ago.

With search crews just months away from finishing their thus-far fruitless sweep of a remote stretch of seabed where Flight 370 is believed to have crashed, officials appear no closer to solving one of the most mind-boggling mysteries of modern times. That stubborn lack of resolution has only increased speculation about what might have happened to the Boeing 777 after it vanished with 239 people on board on March 8, 2014. Some believe officials are simply looking in the wrong part of the Indian Ocean, while social media sites are peppered with comments suggesting they’re looking on the wrong planet: “MH370 was abducted by aliens,” reads a typical tweet.

“We knew this was a very high-profile, publicized event and because it was such a great mystery, there was going to be a lot of scrutiny,” said the Australian Transport Safety Bureau’s chief commissioner Martin Dolan, who is leading the search for the plane far off Australia’s west coast. “We are always open to informed criticism. What we find a bit more difficult is when occasionally people criticize us on the basis of a misunderstanding or a misrepresentation of what we’re doing or saying.”