Who was the guy who spotted Ray Milland going into the elevator?

Maybe I'm dense, but I can't remember who the guy with the beard/glasses/derby was who spotted Ray Milland re-entering the building. Presumably this was the guy who sent out the alert that the killer was in the building? It wasn't McKinley/Jefferson, and it wasn't the guy who tried to steal a drink at Bert's. Was it someone from the previous place, where they kept ordering the green drinks? Thanks.