There are two main duties of a kinsman redeemer. Both revolve around the death of a man’s brother.
In the first case, if a brother died, the man had a responsibility to take care of his brother’s widow. Not only this but he was to marry her and father children in his brother’s name. They would receive his brother’s inheritance, the land that the man took care of. This was a sacred duty and not an easy one as the man would essentially be paying to raise two families. If the brother rejected his right as kinsman redeemer the next in line could claim it. This is what happened in the story of Ruth when Boaz agreed to marry her. He was not the first in line as her kinsman redeemer and had to have the closest relative to her waive his right to redeem her ex husband’s property.
The other right of a kinsman redeemer involved if a brother was wrongfully killed. The kinsman redeemer could seek out justice and hunt down his brother’s killer. If it was an accident the killer could flee to one of twelve cities of refuge. There the elders of the city would hear what happened and determine the proper punishment. If the man left the city of refuge his blood was on his own head if the kinsman redeemer sought justice for his brother’s wrongful death. In the case of a deliberate killing – murder – there were no cities of refuge and the kinsman redeemer was entitled to act as his brother’s avenger.