Goel

Goel (the Go’el HaDahm) is a Hebrew term which comes from the word lig'ol ("to redeem"), hence meaning "redeemer", which in the Hebrew Bible and the rabbinical tradition denotes a person who as the nearest relative of another is charged with the duty of restoring the rights of another and avenging his wrongs. When goel is used in contexts involving revenge for wrongful death, English-language translations of the Bible generally refer to a goel as an "avenger of blood".

In the Book of Isaiah, God is called the redeemer of Israel, as God redeems his people from captivity; the context shows that the redemption also involves moving on to something greater. In Christianity, the title goel is applied to Christ, who redeems his believers from all evil by offering Himself as the Paschal Lamb.

The obligations of the goel include the duty to redeem the relative from slavery, if the latter had been obliged to sell himself into serfdom (Leviticus 25: 48-49); to repurchase the property of a relative who had had to sell it because of poverty; to avenge the blood of his relative; to marry his brother's widow in order to have a son for his brother, in case the brother had not got any son to pass his name forth (Deuteronomy 25:5-6); and to receive the restitution if the injured relative had died (Numbers 5:8).

Numbers 35:9-30 regulates the duties of the goel. The congregation has to judge the case before it puts a murderer in the hands of a goel. More than one witness is needed for conviction. In case of accidental manslaughter, the slayer can save his life by fleeing to a "city of refuge" and staying there for the term of the high priest (who is appointed for his lifetime). Ransom is not accepted for murder. Revenge cannot be taken on the offender's children or parents (Deuteronomy 24:16). Leviticus 25:48-49 gives the order in which the nearest relative is considered the goel in the case of redeeming a slave: brother, uncle, male cousin and then other relatives. The same order was probably observed in the other cases, except in marrying a sister-in-law.

...
Wikipedia