The FBI so far found "nothing sinister" after examining the flight simulator that the captain of the missing Malaysia Airlines passenger jet kept in his home, according to authorities.
The high-tech simulator of Captain Zaharie Ahmad Shah has been the subject of intense interest by investigators amid speculation the 53-year-old aviation veteran may have been responsible for the shutdown of communications and the dramatic change of course of Flight MH370.
Initial scrutiny of the simulator had shown some of the flight plans entered into it were deleted about a month before the ill-fated journey on March 8, prompting Malaysian authorities to hand it over to the FBI for forensic analysis.
"As far as I know, there is nothing sinister on the simulator, but of course that will have to be confirmed with the chief of police," said Malaysia's acting Transport Minister, Hishammuddin Hussein.
Mr Hishammuddin stopped short of plumping for one theory over any other. He said the disappearance was due to "terrorism, hijacking, personal and psychological problems, or technical failure".
As investigators struggle to make headway, 10 aircraft will be tasked on Sunday with scouring the 319,000 square kilometre search area for debris, while eight ships will be deployed to recover items identified from the air to check if they are from the missing plane.
So far, any items retrieved from the sea have been found to be rubbish or flotsam, discarded from fishing boats.
Four ships, three Chinese vessel and HMAS Success are in the search zone already, with more ships expected to arrive on Sunday.
Australian Navy vessel Ocean Shield will set sail from Perth with a black box locator on board, with little more than a week left before the beacon on the flight recorder is expected to stop working as its batteries run out.