The Bible speaks of the importance of making amends and apologizing to those we wrong in Matthew 5:23-24, but to what extent should we attempt to reconcile with our brothers and sisters? If I cannot get in contact with someone that I have sinned against, do I need to search for them until the day I die? Do I need to contact the police or the government to see if it is possible for them to release their contact information so that I can confess and apologize for my sins to the person I have sinned against?
In Matthew’s world, people usually grew up and lived their whole lives in one community. So the scenario you’re asking about was not likely one that would come to mind for the Gospel’s earliest readers. Matthew tells them that the prohibition on murder includes conflicts that are much more mundane. The teaching does not suggest that there shouldn’t be differences of opinion or even conflicts, but that one should not be driven by anger to speak or act in ways that are inconsistent with a life of faith. Acknowledging that one has done so seems to be an important step, even if you can’t apologize directly to the person involved.