It happens in life. This is true. The issue isn't that it happens, but with what's attached to the act, namely reason and how we feel about it. It gets complicated, naturally, but down the line, unless initiated for survival or self preservation, it would be an injustice or an infringement of a truth of some type. I just considered murder to be an infringement of a truth almost always subjectively. I would personally view killing and/or murder as an act of malice, an evil, a type of moral transgression against my own self preserving character. Typically, I view them separate (Murder vs. Killing) That's my subjective stance of morality on killing, which I would suggest is shared by most other self preserving creatures like myself. Our social structures permit hunting, but not for us to kill each other. I agree with this structure, but when we are forced into self preserving modes, like during war, it would be classified as a necessity. Morals, then are about truths. That has been my findings.