By signing off from Malaysian airspace at 1.19 a.m. on March 8 with a casual "all right, good night," rather than the crisp radio drill advocated in pilot training, a person now believed to be the co-pilot gave no hint of anything unusual.
Remember that the two pilots had not asked to fly together. If voice analysis shows that it was the co-pilot (the young devout TROPer with no wife and children who always attends Friday prayers) and the not the pilot (the older Richard Dawkins fan angry about Malaysia convicting people of homosexuality) then the co-pilot would have to be the main suspect.
The sign-off was spoken AFTER someone disabled the transponder.
I would imagine the pilot was probably dead by then.
I’ve thought it was the copilot all along, but I think he would have needed help from outside of the cockpit. I wonder where that came from.