It has also been confirmed this morning that the last person to speak to air-traffic control before the plane vanished 10 days ago is believed to have been the co-pilot, Fariq Abdul Hamid.
Malaysia Airlines CEO Ahmad Jauhari Yahya said at a news conference that initial investigations suggested the first officer was the one who calmly said: "All right, good night".
The home of Mr Zaharie has been searched by police
The men at the controls of the Boeing 777 - Mr Hamid and Captain Zaharie Ahmad Shah - have been one of the focuses of the missing flight.
Both men's homes have been searched and a flight simulator belonging to Mr Zaharie is now in police hands, officials said.
But authorities have stressed that the backgrounds of all the passengers and crew are being checked - as well as engineers who may have worked on the plane before takeoff.
The officials at the news conference did not provide any update on the development that police are investigating a passenger who had aviation experience.
Mohd Khairul Amri Selamat said on social media sites he was a flight engineer working for a Swiss-based private jet charter company.
The 29-year-old's apparent experience means he would have a knowledge of in-flight computer systems and be able to carry out repairs.
The missing plane could have landed at hundreds of locations. Pic: WNYC
However, as an engineer specialising in executive jets, he would not necessarily have had the skills required to divert and fly a Boeing 777.
A senior police official with knowledge of the investigation said: "The focus is on anyone who might have had aviation skills on that plane."
Authorities have also been focusing on the men at the controls - Captain Zaharie Ahmad Shah and his first officer, Fariq Abdul Hamid.
A senior American politician said US intelligence was looking into the pilots.
"I think from all the information I've been briefed on from, you know, high levels within homeland security, national counterterrorism centre, intelligence community, that something was going on with the pilot," said Michael McCaul, the chairman of the House Homeland Security Committee.
"I think this all leads towards the cockpit, with the pilot himself, and co-pilot."
Mr McCaul also suggested hijackers may have landed the plane and be planning to use it "as a cruise missile" in a 9/11-style terror attack.
But a friend of Mr Zaharie has told Sky News he doubts he had anything to do with the Boeing 777's disappearance.
Mr Hamid, left, and Mr Zaharie were the pilots on the missing jet
"He is a very caring person who enjoys life and enjoys flying. He is a very professional pilot," Peter Chong said.
It has also been claimed the plane could have landed at one of more than 600 runways spread across at least a dozen countries.
Researchers at WNYC searched for runways with a length of at least 0.95 miles (1.52km) within a radius of 2,530 miles (4,070km) from the aircraft's last known position.
Some 634 runways, stretching from the India-Pakistan border to the northeast coast of Australia, matched those requirements - many of them in remote, inaccessible places
The number of countries involved in the search for the plane has nearly doubled over the past two days to 26, after satellite and military radar data projected two large corridors the plane might have flown through.
Malaysia Airlines flight MH370 disappeared with 239 people on board
The northern corridor stretches in an arc over south and central Asia, while the other swoops deep into the southern Indian Ocean towards Australia.
Malaysia has announced that it was deploying its naval and air force assets to the southern corridor, with Australian vowing substantial assistance.
Some experts believe the plane is most likely to have flown southwest towards the Indian Ocean, as the northwesterly route would have taken it through numerous national airspaces in an area monitored extensively by satellites.
