The Hebrew word pronounced raw-tsawck means to kill, usually, without intent. The King James Version translates it as "manslayer" (the English word manslaughter means the same because slayer and slaughter are merely different pronunciations of the same Old English word). In ancient times (as in the modern world, usually), someone who killed without intent was still answerable to the authorities of the law, but was not regarded as a murderer. For that reason, a "manslayer" could flee to and take refuge in one of the Levitical "cities for refuge" (unlike the other tribes of Israel, the Levites, as the priesthood, had no tribal territory of their own; they were assigned cities throughout Israel).
"35:6 And among the cities which ye shall give unto the Levites there shall be six cities for refuge, which ye shall appoint for the manslayer, that he may flee thither: and to them ye shall add forty and two cities. 35:7 So all the cities which ye shall give to the Levites shall be forty and eight cities: them shall ye give with their suburbs. 35:8 And the cities which ye shall give shall be of the possession of the children of Israel: from them that have many ye shall give many; but from them that have few ye shall give few: every one shall give of his cities unto the Levites according to his inheritance which he inheriteth." (Numbers 35:6-8 KJV)
"The slayer may flee thither, which killeth any person at unawares"
The cities of refuge were not to prevent justice; they were there to insure that justice was done by impartial investigating authorities - and to prevent a grieving friend or family member from committing a premeditated murder upon someone who had killed innocently.
"35:9 And the LORD spake unto Moses, saying, 35:10 Speak unto the children of Israel, and say unto them, When ye be come over Jordan into the land of Canaan; 35:11 Then ye shall appoint you cities to be cities of refuge for you; that the slayer may flee thither, which killeth any person at unawares. 35:12 And they shall be unto you cities for refuge from the avenger; that the manslayer die not, until he stand before the congregation in judgment. 35:13 And of these cities which ye shall give six cities shall ye have for refuge. 35:14 Ye shall give three cities on this side Jordan, and three cities shall ye give in the land of Canaan, which shall be cities of refuge. 35:15 These six cities shall be a refuge, both for the children of Israel, and for the stranger, and for the sojourner among them: that every one that killeth any person unawares may flee thither." (Numbers 35:9-15 KJV)
The Sixth Commandment is literally "Thou shall not commit murder," not "thou shall not kill." Murderers are guilty; manslayers are innocent.
"35:16 And if he smite him with an instrument of iron, so that he die, he is a murderer: the murderer shall surely be put to death [see What Happens When You Die?]. 35:17 And if he smite him with throwing a stone, wherewith he may die, and he die, he is a murderer: the murderer shall surely be put to death. 35:18 Or if he smite him with an hand weapon of wood, wherewith he may die, and he die, he is a murderer: the murderer shall surely be put to death. 35:19 The revenger of blood himself shall slay the murderer: when he meeteth him, he shall slay him. 35:20 But if he thrust him of hatred, or hurl at him by laying of wait, that he die; 35:21 Or in enmity smite him with his hand, that he die: he that smote him shall surely be put to death; for he is a murderer: the revenger of blood shall slay the murderer, when he meeteth him.
God's perfect and righteous justice states that murderers are not to be "sentenced to life." They are to be executed. Grieve for the victim of a murderer, not for the Satanic murderer (as Christ said, "8:44 Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning" John 8:44; see also Violence) for the LORD commands (again, the decree of Jesus Christ - see 'Before Abraham Was, I AM') "ye shall take no satisfaction for the life of a murderer, which is guilty of death: but he shall be surely put to death" (Numbers 35:31, quoted below).
"35:29 So these things shall be for a statute of judgment unto you throughout your generations in all your dwellings.
Fact Finder: What is the Christian application of "the land cannot be cleansed of the blood that is shed therein, but by the blood of him that shed it" (Numbers 35:33, quoted above)?