I'm going to go the other way on this and say I think that General Hammond does know who killed Armin. It would make sence that he has at least some knowledge. the only 3 people who knew were him, Sam and Jack. Obviously J&S didn't order 'it'. I'm not saying that GH ordered it, but he has to be pretty close to someone who set it up. I think he acts a little more innocent than he really is.
I also think that he has it in him too. He's not always the moral authoriatiran good guy we see him as when he is protecting the SGC.
I also think that he has it in him too. He's not always the moral authoriatiran good guy we see him as when he is protecting the SGC.