Someone could flee there who committed manslaughter, killing his neighbor accidentally without previously hating him. He could flee to one of these cities and stay alive:

The one condemned to die is to be executed on the testimony of two or three witnesses. No one is to be executed on the testimony of a single witness.

“Do not oppress a hired hand who is poor and needy, whether one of your brothers or one of the foreigners residing within a town in your land.

“If two men are fighting with each other, and the wife of one steps in to rescue her husband from the one striking him, and she puts out her hand and grabs his genitals,

“You must not have two different weights in your bag, one heavy and one light.

The Lord your God is the One who will cross ahead of you. He will destroy these nations before you, and you will drive them out. Joshua is the one who will cross ahead of you, as the Lord has said.