God vs Man

That particular Commandment seems to vary depending on the translation you use. Some translations use "kill" while others use "murder". "Kill" can be interpreted in a very strict manner to be against all forms of life termination, while "murder" has a connotation of a more specific type of killing. My $0.02 at the moment.

This eventually will be an area that we will get cleared up upon entry into Heaven, but for now, lets look at some of the things found in the Bible. For instance, King David was blessed beyond measure in his life. He was victorious in battles, thus actively participating in the killing of other people, and God still blessed him, but did tell him that he would not be the one to build His temple, due to the amount of bloodshed on his hands. So we see that King David was blessed abundantely, but also did not get to do the desire of his heart, and build the temple of God. Like I said in the beginning of this post, we will not know for sure the answer to some of our questions until we meet God face to face. And come to think of it, even then, we may not care about those unanswered questions of this life and may be overjoyed with being in His presence.

I think there is a difference between killing someone to prevent others from harm and murdering someone out of anger.

the correct translation says not thou shalt not kill but that "thou shalt not murder" there is a vast difference !