Numbers 35:12 (NLT)
These cities will be a place of protection from a dead person's relatives want to avenge the death. A slayer must not be put to death before being tried by the community.
15 These cities are for the protection of Israelites, foreigners living among you, and traveling merchants. Anyone who accidentally kills someone may flee there for safety.
Numbers 35:21 (NLT) - 21 Or if someone hates another person and hits him with a fist and he dies, it is murder. In such cases, the avenger must put the murderer to death when they meet.
Numbers 35:22 (NLT) - 22 “But suppose someone pushes another person without having shown previous hostility, or throws something that unintentionally hits another person,
24 If this should happen, the community must follow these regulations in making a judgment between the slayer and the avenger, the victim’s nearest relative:
25 The community must protect the slayer from the avenger and must escort the slayer back to live in the city of refuge to which he fled. There he must remain until the death of the high priest, who was anointed with the sacred oil.
28 because he should have remained in his city of refuge until the death of the high priest. But after the death of the high priest the one who committed manslaughter may return to the land of his property.
Numbers 35:30 (NLT)
"All murderers must be put to death, but only if evidence is presented by more than one witness. No one may be put to death on the testimony of only one witness.
Numbers 35:31 (NLT)
Also you must never accept a ransom payment for the life of someone judged guilty of murder and subject to execution. Murderers must always be put to death.