Malaysian authorities said Sunday they were investigating the flight simulator that the pilot of the missing Malaysia Airlines jet kept at his home, NBC News reported. Investigators searched Capt. Zaharie Ahmad Shah's home Saturday, as well as the home of co-pilot Fariq Ab Hamid. In addition to an ongoing police probe into all crew and passengers on board flight MH370, police were also investigating engineers who may have been in contact with the plane before take-off. Malaysian Prime Minister Najib Razak confirmed Saturday that the jet carrying 239 people could have only taken the route it did if someone intentionally flew it off course. Meanwhile, authorities on Sunday said the search area for the plane had been "significantly expanded," and that the number of countries involved in the hunt for the aircraft, which vanished nine days ago, had increased from 14 to 25.