if you go into the first level in the museum heist, in the part where you play as bentley, once you get to the computer room where you hack the security, turn left or right ( dosn't really matter) there will be a chalkboard of Le Paradox's blimp, there are clearly shown notes, but if you look around on the chalkboard, there in some very faded messages that are difficult to read...
one says: "clockwerk have anything to do with le paradox's scheme?" and followd by some numbers that could be a date or something.