I watched that video posted above and even being an extreme rookie I was pretty shocked that he was so adamant about it being suicide. I could understand him saying that it is his opinion that it is possible but he flat out said it was suicide, no if, ands, or buts. I'm leaning towards some type of stroke or intoxication since he sounded out of it from the start. Carbon monoxide might be a possibility but I probably know less about airplanes than anyone on here so I'm just throwing that out there. I'm not on board with the struggle in the cockpit theory. That doesn't explain the troubled speech from the beginning unless he was trying to alert ATC in a code type of way?
The airplane side of it is way over my head but I used to work in law enforcement and have conducted investigations so that's what gets my attention here.