It is still incorrect to do bad for the sake of the goodness for your children. So, the murderer murders for his children? Is he doing it for their own good? Have you ever thought that the murdered is the provider of his own family? That a mother is waiting for her son's return or innocent children waiting for their father to enter their front door, impatient for his return? Or a struggling family that awaited his salary to buy their own basic fundamentals of human needs?
The emotional side of us humans react to the family of this "murderer". But rational people thinks this way. The people who created the law and abides with it still sticks to it in spite for the "good sake" of his family. Laws are like this. 
Regardless whatsoever, a sinner is a sinner. But it is divided into two, the unintended and the intended. Life is meant to test you and drive you to your very corners of sanity, edging you and threatening to push you off of your cliff of living.
So, what happens if this "murderer" is caught and faced a sentence? 15 years in prison? Who will have to take care and guide his children to the betterment he they would be guided by his "wrongly" doings? This "murderer" as you speak of must change his ways of living for the sake of his children to not be influenced that doing bad for the sake of good.. it is surreal but that is what it is.      ~RaccoonTurtle:3