you dont need to be a member of the militray to be tried for treason.
i dont think, you just need 3 witnesses

treason DOES carry the death penalty
According to CNN, you need two witnesses or a confession in open court. And, you're right, you don't need to be military to be charged with treason.

I still think he's more guilty of stupidity than anything else. But, I also think he's going to get some time behind bars, even if he does cooperate.