It is argued that judicial killing is not murder and that the Ten Commandments teach thou shalt not murder. Here is one explanation expressing this point:
There are two different Hebrew words (ratsakh, mut) and two Greek words (phoneuo, apokteino) for “murder” and “killing.” One means “to put to death,” and the other means “to murder.” The latter one is the one prohibited by the Ten Commandments, not the former. In fact, ratsakh has a broader definition than the English word “murder.” Ratsakh also covers deaths due to carelessness or neglect but is never used when describing killing during wartime. That is why most modern translations render the sixth commandment “You shall not murder” rather than “You shall not kill.” However, a very large issue can arise depending on which translation one studies. The ever-popular King James Version renders the verse as “Thou shalt not kill,” therefore opening the door to misinterpreting the verse altogether. If the intended meaning of “Thou shalt not kill” was just that—no killing—it would render all of the God-endorsed bloodletting done by the nation of Israel a violation of God’s own commandment (Deuteronomy 20). But God does not break His own commandments, so, clearly, the verse does not call for a complete moratorium on the taking of another human life. https://www.gotquestions.org/you-shall-not-murder.html
A careful examination of the Scripture reveals that this argument is false. Firstly, within the very explanation the writer acknowledges that ratsach not only mean murder but accident death which we call manslaughter. This is not murder.
Num 35:22-25 But if he thrust him suddenly without enmity, or have cast upon him any thing without laying of wait, (23) Or with any stone, wherewith a man may die, seeing him not, and cast it upon him, that he die, and was not his enemy, neither sought his harm: (24) Then the congregation shall judge between the slayer and the revenger of blood according to these judgments: (25) And the congregation shall deliver the slayer [H7523 Ratsach] out of the hand of the revenger of blood, and the congregation shall restore him to the city of his refuge, whither he was fled: and he shall abide in it unto the death of the high priest, which was anointed with the holy oil.
Deu 4:42 That the slayer [Ratsach H7523] might flee thither, which should kill his neighbour unawares, and hated him not in times past; and that fleeing unto one of these cities he might live:
Secondly, God did command that people who commit ratsach should face the same thing.
Num 35:30 Whoso killeth any person, the murderer [H7523] shall be put to death [ratsach H7523] by the mouth of witnesses: but one witness shall not testify against any person to cause him to die.
How could it be possible that God could command things that the Ten Commandments forbids? In short, God could command any form of death in the Scriptures because God seeks to secure the sentence of death in order to give mercy not to kill people. Please see the booklet called Ministration of Death for a full explanation of this.
Thirdly, the word muth [H4191] in Scripture is used to describe murder, and assassination. Saul desired to unlawfully murder David:
1 Sam 19:1,2 And Saul spake to Jonathan his son, and to all his servants, that they should kill [H4191] David. But Jonathan Saul's son delighted much in David: and Jonathan told David, saying, Saul my father seeketh to kill thee: [H4191] now therefore, I pray thee, take heed to thyself until the morning, and abide in a secret place, and hide thyself:
Saul ordered the unlawful murder of the priesthood:
1 Sam 22:17 And the king said unto the footmen that stood about him, Turn, and slay the priests of the LORD; because their hand also is with David, and because they knew when he fled, and did not shew it to me. But the servants of the king would not put forth their hand to fall upon the priests of the LORD. And the king said to Doeg, Turn thou, and fall upon the priests. And Doeg the Edomite turned, and he fell upon the priests, and slew [H4191] on that day fourscore and five persons that did wear a linen ephod.
The assassination of Isbosheth:
2 Sam 4:7 For when they came into the house, he lay on his bed in his bedchamber, and they smote him, and slew [H4191] him, and beheaded him, and took his head, and gat them away through the plain all night.
Absalom orders the unlawful murder of his half-brother Amnon:
2 Sam 13:28 Now Absalom had commanded his servants, saying, Mark ye now when Amnon's heart is merry with wine, and when I say unto you, Smite Amnon; then kill [H4191] him, fear not: have not I commanded you? be courageous, and be valiant.
Athaliah murders all the king's sons except Joash:
2 Kings 11:2 But Jehosheba, the daughter of king Joram, sister of Ahaziah, took Joash the son of Ahaziah, and stole him from among the king's sons which were slain; [H4191] and they hid him, even him and his nurse, in the bedchamber from Athaliah, so that he was not slain.
Notice the translation in the New King James:
2 Kings 11:2 But Jehosheba, the daughter of King Joram, sister of Ahaziah, took Joash the son of Ahaziah, and stole him away from among the king's sons who were being murdered; [H4191] and they hid him and his nurse in the bedroom, from Athaliah, so that he was not killed.
Another assassination using the word muth and the translation in the NIV:
2 Kings 15:25 But Pekah the son of Remaliah, a captain of his, conspired against him, and smote [H5221] him in Samaria, in the palace of the king's house, with Argob and Arieh, and with him fifty men of the Gileadites: and he killed [H4191] him, and reigned in his room.
NIV 2 Kings 15:25 One of his chief officers, Pekah son of Remaliah, conspired against him. Taking fifty men of Gilead with him, he assassinated[H5221] Pekahiah, along with Argob and Arieh, in the citadel of the royal palace at Samaria. So Pekah killed [H4191] Pekahiah and succeeded him as king.
Is it possible for the wicked to so called righteously slay a person?
Psa 37:32 The wicked watcheth the righteous, and seeketh to slay [H4191] him.
Psa 109:16,17 Because that he [the wicked] remembered not to shew mercy, but persecuted the poor and needy man, that he might even slay [H4191]the broken in heart. As he loved cursing, so let it come unto him: as he delighted not in blessing, so let it be far from him.
Jeremiah warns against those seeking to murder him:
Jer 26:13-15 Therefore now amend your ways and your doings, and obey the voice of the LORD your God; and the LORD will repent him of the evil that he hath pronounced against you. (14) As for me, behold, I am in your hand: do with me as seemeth good and meet unto you. (15) But know ye for certain, that if ye put me to death, [H4191] ye shall surely bring innocent blood upon yourselves, and upon this city, and upon the inhabitants thereof: for of a truth the LORD hath sent me unto you to speak all these words in your ears.
So the word muth can indeed be used to mean murder and assassination and the word ratsach can be used for accidental death. This proves false the claim that muth is somehow only for righteous killing and ratsach for murder.
Lastly, regardless of how this is defined both murder and judicial killing employ lethal force. Is the use of force part of God’s kingdom?
The earth was dark through misapprehension of God. That the gloomy shadows might be lightened, that the world might be brought back to God, Satan's deceptive power was to be broken. This could not be done by force. The exercise of force is contrary to the principles of God's government; He desires only the service of love; and love cannot be commanded; it cannot be won by force or authority. Only by love is love awakened. To know God is to love Him; His character must be manifested in contrast to the character of Satan. DA 22.
Do we comprehend the significance of the above statement? God can’t use lethal force as part of His kingdom. Do we accept this statement as inspired? The response comes that we must get our teaching from Scripture. I would suggest the most perfect example of the refusal to use lethal force is the earthly life of Jesus. Do we accept the words of Jesus?
Mat 5:39 But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also.
Did Jesus demonstrate this as part of His character? Secondly, if judicial killing is part of God’s character then this must have been revealed in the earthly life of Jesus. Yet it is nowhere revealed that He carefully weighed the life of a person and then ordered them put to death.
What answer can be given to the person who says to the Lord, “I followed your example in the Old Testament when I put this evil doer to death.” Shall it be said to such a person, “You followed the wrong example, that part of Scripture is not for you to follow.” Can you see that it makes things very difficult? It is time to put the muth argument to death and believe the truth that thou shalt not kill means thou shalt not take life.
The earthly life of Jesus reveals for us the correct interpretation of the commandment "thou shalt not kill." Jesus never killed anybody.