Damn, I'm pretty sure I'm missing some context here.
However all rights are defined under the law. Usually through some sort or man made(adopted) protection, such as a constitution. We like to believe some of them are inalienable but that's just not true. It's the difference between ethics and morals for example. Aside from these rules we operate society under; human beings still retain their free will, which includes the free will to commit murder.
That's how I see it. I agree it's not right to take the life of someone but that opinion must be shared, which I think it is by most of us. Thankfully. Still the written law is a man made construct that is only enacted after someone uses their free will in violation of these rules... well at least until Minority Report becomes fact and renders my opinion utterly obsolete.
Still if I get this right, you're just debating the difference in definition of murdering and killing? Both are homicide in relation to human beings. Is driving while texting and killing a person any better than shooting a punk in the face?