The world was shocked earlier this year as horrifying footage showed the plane plummet at a near-vertical descent.
The plane crashed in southern China in late March killing all 132 passengers on board.
Flight data indicates the plane was intentionally crashed by someone in the cockpit, according to the Wall Street Journal, which cites people familiar with US officials’ preliminary assessment.
“The plane did what it was told to do by someone in the cockpit,” said one of the sources.
Officials announced that the cockpit voice recorders was found although damaged, and they have not yet disclosed whether any information was able to be retrieved from it.
Chinese authorities have not flagged any mechanical or computer problems with the plane, leading American officials involved with the investigation to begin looking at the pilots.
China Eastern, the airline that was operating the plane, said in a statement to the Wall Street Journal that the pilots’ health and family conditions were of no concern and that their financial status was also good.
However, unverified allegations have gone around Chinese social media saying one of the pilots had complained about toxic work culture and the loss of his life savings due to Chinese real estate company Evergrande’s default just a few months prior to the crash.