An oxymoron. Murder is wrong by definition, and there is only rightful killing. There is, also by definition, no rightful murder.
Only rightful killing, and rightful violence or harm; No rightful murder.
We kill for divine providence and our god given right to assert dominance, or we kill because it gives us what we want more quickly. By divine command or convenience, we justify the killing of both humans and our less gifted, but more removed, animal and plant relatives.
I am questioned, as a purported "vegan," why cutting down grass is not as bad as cutting down cattle. The only meaningful answer I can provide is: I intuit that it is worse.
I do not feel the need to argue that cattle matter. But I would need to argue that they are one and the same.
They are both wrong, and wrong under different conditions. Humans are not immediately or obviously wrong in killing each other, and they're not wrong wrong to kill lesser animalia, plantea, fungi, etc.
As modern people we know intelligence is an emergent property, and we recognize the uniqueness of all individuals. We do not all acknowledge the difference in value between individuals; Modern "liberals" declare equality amongst all individuals, beyond equality of law.
Equality of law, is not equality of value.
Animals have value, but not equal value to humans. Value, like intelligence, is an emergent property. We should not take offense to suggestions of inequality of value between individuals just as we take offense to suggestions of races, species, plants, liberals between each other, or conservatives between each other.
We are only worth what we make ourselves to ourselves, and to each other.