why did general Shepard kill roach at the end of the second game?
Nice troll, but since that's COD, I can answer that too: Shepard killed them both because he had a scheme set up with Makarov to make them the most powerful men in their countries. When he sent them to get all of Makarov's info in the safehouse, he got paranoid and thought they found out about the plan. Thus, he killed off the remainder of TF141.