Jennifer killed Michael. Michael was human. Jennifer's act was premeditated and malicious. To justify the moral principle, we may argue from above or from below. That murder was wrong. . . .
Murder is wrong.
Often this takes the form of one fundamental moral principle from which everything else can be derived. This drive is very old, and not purely academic. What you would want others to do unto you, do unto others. Murder is wrong. Good for their own sake.