You did? Ah well, I'll just have to change that. I think I thought it was a spelling mistake or something and changed it.
OK, Marxus ducks in behind the pillar just as the guard (a serpent one if you must know) walks to the middle of the corridor at his end and turns to look down it. Both of you are behind cover so he can't see you. Another guard does the same thing at Andrei's end.
Behind the pillars is a small alcove that stretches past all the pillars with a door in the middle, placed discretely behind a pillar (no. 3).
OK, that's not very long to wait as the guards look down the corridors and see nothing of interest. They then turn back to face the corridor that they came from and walk forwards. You are still un-noticed.
Oh and if anyone's thinking of ,aybe just shooting someone without trying any stealth moves they'll lose the whole team brownie points