We found out later in the season that Bernard is made in the image of Arnold. Also in earlier episodes, Bernard himself asks Ford about Arnold. How is it possible that no one in the whole park knows who Arnold is, and what he looked like?
I can understand that it has been many years(30?) since the park opened and new people might not know about the 2nd partner, especially since Delos will not want anyone to know about someone so important committing suicide just before opening of the park. But Elsie points out in one episode that Bernard 'has been there since ever'. I am not sure if it was mentioned or I forgot when Ford introduced Bernard in the park, but it seems a little improbable that no one even back then knew about Arnold. Also Bernard being a programmer himself could easily see at any point the code commits made by Arnold. Maybe it was one of those 'it doesn't look like anything to me' thing, maybe.
But the massacre at the church location must have been a huge thing, even if Delos hushed it up. Someone must know, right? Speaking of Delos, someone in higher management must have known about Arnold(William's father-in-law?).
On a sidenote, isn't it too cocky and careless of Ford to keep a photo of him(at a very young age) with a guy looking like Bernard in his office. Ok, so Bernard probably wont even see Arnold in that photo, but he can't be the only one visiting his office. Ford seems to spend an awful lot of time at his other underground office anyways.