There isnt anything you can do about outlaws. They can come and run around your town like nothing happened. It would be good to utilise the towny ranks of Officer that allow you to jail outlaws that get killed by you in town this way. That way being an outlaw in a town you're not wanted on can have consequences. Considering how cheap it is to bail people this wouldnt ruin gaming experience rather enchanse it. On the contrary,outlaws shouldnt be able to combat tag you first otherwise it would be pointless to make your town raidable to jail someone. The Officer must initiate the combat tag.