No trace of the plane has been found more than a week after it vanished but investigators believe it was diverted by someone with deep knowledge of the plane and of commercial navigation.
Malaysian Prime Minister Najib Razak said on Saturday evidence pointed to a deliberate diversion of the flight, given the controlled way it was apparently turned around and flown far to the west of its original route from Kuala Lumpur to Beijing.
A flight engineer is responsible for overseeing systems on a plane during flights to confirm they are working correctly and to make repairs if necessary.
(Read more: MH370: Timeline of latest developments)
As an engineer specializing in executive jets, Khairul would not necessarily have all the knowledge needed to divert and fly a large jetliner.
Khairul had said he worked for a Swiss-based jet charter firm called Execujet Aviation Group, but the company declined to say whether it still employed him. In a picture posted on Khairul's Facebook account in 2011, he identified himself as an employee of Execujet's Malaysian operations.
"We can't disclose anything. We want to protect the family's privacy," an official at the company's Malaysian office said.
(Read more: India puts search for missing plane on hold - officials)
Khairul, a father of one daughter, had recently bought a house on the outskirts of the Malaysian capital, Kuala Lumpur, and had more than 10 years experience as a flight engineer, his father Selamat Omar told Reuters. He declined to say whether he believed his son could have been involved in any foul play.
Selamat said he and other family members were supposed to visit Khairul's new house this month. But Khairul had told his father on Thursday he had to go for a job in Beijing and that they would reschedule. That was the last time they spoke.
"Khairul was doing well in his job and was a good son. He would come visit us at least once a month," Selamat said.