How did the cities of refuge protect someone who accidentally killed another person?

Les teaches that during the days of the cities of refuge, a good Jew, as soon as he realized what he had done and knew he would be accused of killing someone, could run to a city of refuge. There he could tell his situation to the city fathers. If the city fathers maintained that he was innocent of premeditated murder, he was set free and could go back to his farm. The reason was that he was not guilty if he did what he did in total ignorance. Les connects this backdrop to Israel's response to their Messiah: had they known who He was and demanded His crucifixion, they would have had to be put to death like a common murderer, but they escaped because they did not know what they did. He also ties it to 1 Corinthians 2:7-8, where Paul says the princes of this world did not know, for had they known, they would not have crucified the Lord of glory, and to the Lord's words, 'Father forgive them, they're ignorant, they don't know what they're doing.'