I think it's safe to assume? that the flight crew were incapacitated in some way. If you have a problem, surely as a pilot, you would decend towards a blooming great mountain range.
A question if I may. Looking at a previous post which listed the decent rate of the aircraft. It started out decending at 2300ft/min, then it went to 3050ft/min all the way down to 4225ft/min and then back up the scale to the point of impact. Is this normal if the aircraft was on autopilot? I would have thought that if you set a rate of decent on the panel, it will maintain that number until altered by further inputs.
By the way, I'm not a pilot but am a fully trained aircraft engineer.