Many murders occur when the killer has a paranoid mind-set. He imagines the other person intends to kill him. Muslim propaganda utilizes this factor every day. They portray the west as out to destroy them. Thus, they are guiltless if they strike preemptively.
Everyday we witness murder as a part of everyday life under Islam. Public executions for adultery by stoning, for apostasy by beheading and for blasphemy by hanging. Christians and Jews are burned inside their places of worship simply by being there.