The mystery over missing Malaysia Airlines flight 370 deepened Thursday as the Wall Street Journal reported that U.S. investigators suspect the jet stayed in the air for four hours past its last confirmed radar position.
U.S. counterterrorism officials are pursuing the possibility that a pilot or someone else on board the plane may have diverted it toward an undisclosed location after intentionally turning off the jetliner's transponders to avoid radar detection, the newspaper reported, citing one person tracking the probe.
The report suggests the Boeing 777 could have flown on for additional distance of about 2,200 miles, potentially reaching the border of Pakistan or as far as destinations in the Indian Ocean.
It said the investigators were reviewed data automatically downloaded and sent to the ground from the Boeing Co 777's Rolls Royce engines as part of a standard monitoring program.
The report came after a leading air safety investigator told NBC News on Wednesday that the hunt for MH370 is likely to turn into a criminal inquiry as mounting evidence points to a deliberate act.