You shouldn't murder people.
John is walking his dog when a careless man on a bicycle runs into his dog at full speed hurting the dog badly.
James wants to seek revenge on the careless man.
John tells the man to stay there while he calls the police and a vet for his dog.
John gets into such a rage that he pounds the man into the ground, beating him until the man dies.
John eventually is satisfied when the careless man is tried for criminal negligence.
John is arrested for murder and is vilified in the press ruining his life forever.