Twelve days into the mystery of what happened to Malaysia Airlines Flight 370 and the 239 people on board, more clues seem to raise only more questions.

The latest news about the investigation and search for the plane includes:

-- An NBC News report that sources familiar with the investigation say data from the plane's communications systems indicate someone manually programmed a turn into the Boeing 777's navigation system 12 minutes before a voice from the cockpit said, "All right, good night," to Malaysian air traffic controllers.

If that is what happened, it could mean that whoever was at the controls had already planned a sharp turn to the west — well off the jet's planned Kuala Lumpur-to-Beijing route — before the seemingly routine sign-off.

That turn is why the search for the jet has extended thousands of miles south across the Indian Ocean and thousands of miles north into Central Asia.

Authorities have said they believe the voice heard saying good night was that of co-pilot Fariq Abdul Hamid.

Whether he or pilot Zaharie Ahmad Shah or someone else programmed a course change into the navigation system is not known.

Accounts have varied as to exactly when that occurred. Also in the minutes around that good night message is when most of the plane's communications and tracking systems went dark. The lack of data from those systems is why the search area is so vast — authorities aren't sure which direction the plane went after it headed west.

-- Word from Malaysian officials that some files were recently deleted — perhaps in early February — from a flight simulator in the home of Flight 370 pilot Zaharie Ahmad Shah. Investigators are attempting to restore the files to see if they have any connection to the missing jet.

-- A narrowing of the search by Australian authorities. According to The New York Times, "the initial search area that Australian officials announced Tuesday has been reduced by half, using new data analysis of the plane's likely fuel consumption, John Young, general manager for the agency's emergency response division, said Wednesday. The new area of focus in the Australian-led part of the search covers 89,000 square nautical miles, roughly 1,200 nautical miles southwest of Perth, Mr. Young said."

The Times says that search zone is roughly the size of Italy.

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