Title is self explanatory. Don't complain if you come here and read spoilers.
I've yet to see any video proof of anyone getting Silent Assassin on this level, despite some claiming they have. I have found a way to get through it undetected by subduing and hiding two non target NPCs, and signature killing the target, yet I only get a Professional rating.
I can only assume if it IS possible, there must be some way to get the Silent Assassin bonus somewhere, but I don't see how. Any clues from those whom might have achieved this?