I know what it feels if someone you trusted betrayed you and took away everything from you but we shouldn't put the law in our hands. They should have not killed them because sometime in their life they became friends or if not, atleast partners. It is a sin in the eyes of God to kill people. They should have let the police to took care of the matter. Because of the killing, they just made their life more miserable. I'm praying for them to reflect on what they did and I hope that they will reciver from it very soon.