I decided to Excommunicate Overseer Campbell with the Heritics mark instead of assassinating him since I'm going for an alternate playthrough than my first, much bloodier, playthrough.
The incredible twist came when attempting to retrieve my gear during the mission 'Flooded District'. Wandering around the bottom level near your equipment is Overseer Campbell as a Weeper. He just shows as 'Weeper' when inspected but is identifiable by the Heritics Mark I gave him during the mission to eliminate him.
I thought this was very cool and really registered an emotional response. Your actions truely do shape the world you play in and have consequences. Bravo on the developers part by adding in these small, but very meaningful additions.