HONG KONG/TOKYO - Some trace of the passion that Mr Zaharie Ahmad Shah had for flying can be found in the trail of e-mail exchanges and online message board posts that detail the Malaysia Airlines pilot's construction of a state-of-the-art flight simulator at home.
Now the stack of computer monitors, graphics cards and software he painstakingly sourced and improved is being pored over by investigators trying to make sense of the disappearance more than two weeks ago of the passenger jet he was piloting.
There is no evidence that Mr Zaharie was responsible for the loss of Flight MH370, which had 227 passengers and 10 crew, including the 53-year-old captain, aboard.
In fact, many in the online community of specialist vendors and flying enthusiasts whom Mr Zaharie turned to for components and advice say it is common for pilots to enjoy flying so much that they have simulators at home.
"Many pilots contact me interested in making 'home'simulators. Mr Zaharie along with some others pilots actually used my motion controllers to upgrade the realism of their simulators by building motion platforms," Thanos Kontogiannis, a California-based aviation enthusiast who helped Mr Zaharie build the simulator, posted on his blog on Monday.
Mr Kontogiannis, whose LinkedIn profile and blog describe him as a San Diego-based Qualcomm employee who builds motion controllers in his spare time, did not respond to requests for comment.
But with investigators convinced that the missing plane was diverted thousands of miles off its scheduled course from Kuala Lumpur to Beijing by a skilled aviator, attention has focused on Mr Zaharie and the 27-year-old co-pilot, Fariq Abdul Hamid.
Malaysian police seized the simulator last week from Mr Zaharie's gated home in an upscale suburb west of Kuala Lumpur.
Games he was running from the Microsoft "Flight Simulator"series and the latest "X-plane" title were being examined.
"Looking through the flight logs in these simulator games is a key part of the investigation," said an official with direct knowledge of the investigation into Zaherie and his co-pilot.
"X-plane 10 was interesting to investigators because it was the latest thing Mr Zaharie bought. Also it is the most advanced out there and had all sorts of emergency and combat scenarios."
Malaysian investigators have asked the FBI for help in memory recovery after discovering some data was deleted on Feb 3.
Mr Zaharie spent thousands of hours in the virtual cockpit of the machine playing flying games or boosting its capabilities.
He seemed proud of the results.
On the evening of Nov 17, 2012, he posted a picture of his newly-finished simulator and its specifications to an online forum, calling it "awesome" and saying it was his "passion". He said it was "time to take to the next level of simulation" with a motion controller and that he was "looking for buddies".
A motion controller makes the chair of the simulator pitch and turn like in a real cockpit to simulate the climbs, descents and banked turns of a real plane. Mr Zaharie's set-up also included a centre pedestal, where aircraft controls sit, and overhead panel.
It's impossible to estimate exactly how much Mr Zaharie spent on his simulator, but rough estimate by Reuters shows it was likely to be well in excess of $7,000.
Flight simulator costs vary depending on parts used. For example, a replica Boeing-737 seat on Flight Simulator Center, a website with simulator parts, costs almost US$5,000 (S$6,371). An overhead panel listed on another website costs US$800.
The software, currently a focus for investigators, would have allowed him to practice landing at more than 33,000 airports, on aircraft carriers, oil rigs, frigates, which pitch and roll with the waves, and heli-pads atop buildings.
Other software Mr Zaharie was using would have let him to use the Internet to fly with friends and he could have simulated "a lot of malfunctions, emergencies, go-arounds, return-to-base or divert with fairly exact procedures", according to Naoya Fujiwara, a flight simulator expert from Japan.
He could have simulated any weather and even downloaded real weather, wind and temperature data from a professional server, Mr Fujiwara said.
Given the large amount of cheap memory loaded onto modern computers, it's unlikely Mr Zaharie would have had to erase his flight data for technical reasons - so it remains unclear why some of the data was erased on Feb 3.
"Today storage capacity is not a problem for a computer running simulators," said Fernando Nunez Correas, a simulation software developer using some of the same components as Mr Zaharie.
Erasing data may have been part of a regular maintenance routine or done to help improve the simulator's performance, flight simulator users say.
He could not have practiced evading radar, for instance, because radar is not part of the simulation, Mr Nunez said.