Police chief Khalid said investigators had taken the flight simulator for examination by experts.
Earlier, a senior police official said the flight simulator programs were looked at closely, adding they appeared to be normal ones that allowed players to practice flying and landing in different conditions.
Police sources said they were looking at the personal, political and religious backgrounds of both pilots and the other crew members. Khalid said ground support staff who might have worked on the plane were also being investigated.
A second senior police official told Reuters investigators had found no links between Captain Zaharie, a father of three grown-up children and a grandfather, and any militant group.
Postings on his Facebook page suggest the pilot was a politically active opponent of the coalition that has ruled Malaysia for the 57 years since independence.
A day before the plane vanished, opposition leader Anwar Ibrahim was convicted of sodomy and sentenced to five years in prison, in a ruling his supporters and international human rights groups say was politically influenced.
Asked if Zaharie's background as an opposition supporter was being examined, the first senior police officer would say only: "We need to cover all our bases."
Malaysia Airlines has said it did not believe Zaharie would have sabotaged the plane, and colleagues were incredulous.
"Please, let them find the aircraft first. Zaharie is not suicidal, not a political fanatic as some foreign media are saying," a Malaysia Airlines pilot who is close to Zaharie told Reuters. "Is it wrong for anyone to have an opinion about politics?"
(Read more: Malaysian Prime Minister: MH370 actions were deliberate)
Co-pilot Fariq was religious and serious about his career, family and friends said.
The two pilots had not made any request to fly together.
Experts doubt militant groups involved
With no clear motive established as to why someone diverted the plane, Khalid said all possibilities - hijack, sabotage, or personal or psychological problems of someone on board - were being investigated.
Transport Minister Hishammuddin said authorities had not received any ransom or other demand. "That makes if very difficult for us to verify whether its a hijacking or terrorist," he said.
Southeast Asia's homegrown Islamist militant groups, such as Jemaah Islamiah (JI), which carried out the Bali bombings in 2002, have been quiet in recent years after security forces either arrested or shot dead numerous members.