The Gs knew Zach's role. They had to.
If Zach is a normal C, why did the BG protect him? Why on earth? One explanation would be that the D investigated the BG (thus realized I'm not the BG and easily convinced him about his role) and that he also investigated Zach. But even in this case, why would the BG protect Zach the normal C?
If Zach is the BG, he protected himself. Still, why did the Gs try to whack him if they didn't know his role? They tried to whack him because they knew his role.
If Zach is the D, then the BG knew that and that's why he protected him. How could the BG know that Zach is the D? Only if Zach the D investigated the BG and told eachother about their roles.
So, all in all, Zach wasn't randomly protected (it's crazy if he was, that's why it's impossible

). He was protected most likely because he protected himself, or because his role was known to the BG (less likely). In any case, the Gs knew his role.
So, @
Zacheryah, no matter your role, tell us who was investigated in the last 3 days.