God may bless these new Christians, but the people they murdered surely won't. Nor will their relatives. The genocide these people took part in is second only to the Holocaust.
I hope that those who did evil have repented and changed their ways but that should not be the end of it. It annoys me how some people cheapen God's grace by saying that if some murderer repents, that murderer should not face the ultimate human justice. Just because some people might have a different relationship to God does nothing to erase the evil that they did and it does nothing to lessen the need for judgement and justice on earth. And the victims of injustice should be helped when possible, whether they are Christian or not.