Murder in self-defense really really depends on the circumstance, like, if the guy was just going to hit him around a bit, and he murdered him accidentally, I knew a guy who told me his mate got into a fight, punched the guy, he fell back hit his head off the kurb and died, he got jail for 4 years, weirdly enough the exact same thing happened again when he got out, he got in a fight punched the guy he fell back hit his head off the ground and died, even video evidence proved this was just an accident, both times, the guy got jail for 12 years the next time, as far as i'm aware he's still serving his sentence, I still have no sympathy for him, although I think it's extremely unlucky.
It's part of life, you do things and have to accept the consequences that could possibly happen, have a family, something bad could happen to them, get into a fight and by some extreme luck, they die and you go to jail... I know it's not fair, but thats what life is like sometimes, we gotta make the best of it, share the best moments we can with our loved ones while we can before the inevitable happens.
And like I explained to Ramone in a game, the example I gave, the kids son didn't die, so to me it's still murder in cold blood, if the guy killed his son, and he done it, then i'd call it retaliation of extreme circumstances, i'd still not have sympathy for the crime he commits, but i'd have sympathy for his lost son.