 Olaf died in 1006 , and Olaf 's widow Thorgerd subsequently directed a number of revenge @-@ killings herself , including that of Thorkel , a man who had witnessed Kjartan 's death but been indifferent to it and had not intervened . Bolli was killed by Olaf 's sons and their allies in a raid led by Thorgerd . Some twelve years later , Gudrun , with the help of her friend Snorri Goði , had a number of Bolli 's murderers killed in revenge . 
