Jumping Jezus, hasn't anyone read the book? The commandment is "Thou shalt not commit murder!", not 'kill', which would, upon any thoughtful examination at all, be absurd!
The most likely word used was a form of ra-tsach
. It is used only towards humans (although the causative-like forms of mooth
is used towards humans too).
At both Ex 20:13 and De 5:17, ra-tsach
is used. While the contexts in which the word is used more often evidences a nuance of a 'premeditated act,' at times it does not--for example De 4:42; Num 35:6, 11, 12, etc.
The word mooth
, in the causative-like form, is probably the most commonly used, and is often found in combination. Num 14:15 is an example of its usage, as also Josh 8:24-27 area (if my memory serves me well--I'll double check).
However, the act of ending a life is exactly the same--no ifs ands or buts about that--thus it simply boils down to the reason (or lack of reason). In the story related in the work entitled Joshua, YHWH helps out with the killing just as much as the Israelite soldiers. When Uzzah attemped to balance the ark, as the wagon had been upset by the oxen, by reaching out and steadying it with his hand, YHWH blew his top and killed him on the spot.
When a person of a tribe accidently killed someone unintentionally, he could escape revenge by running off to one of the 'refuge cities,' and as long as he stayed there until the high priest of that time died, he would be free of the death penalty. If he were found by the 'blood revenger' outside that city, that revenger could legally kill him on the spot--without being in the wrong. If that's not murder, then really, what is?
Therefore, YHWH's giving the tribes a law clause which stipulates that it is wrong to, let's say here, kill another tribe member by ill-intent, and kills poor ole Uzzah on the spot for simply trying to do what was a surely natural, human 'knee-jerk' reaction, I say we find a personality conflict.
At any rate, whether we translate the word at Ex 20:13 (MS; the LXX gives a different order) as 'kill' or 'murder,' it makes no real big difference because the verb can be and is used in both instances (with or without intent [premeditation]) and because killing a person simply due to anger, is murder--regardless.