Oh yeah, i just remembered. Before i got the hard answers quest, i had to sneak or battle through a museum. I did the sneaking way, good thing i had thief light armor from a earlier quest i did.
I stole a few pretty soul gems along the way, only 2 guards found me. The rest i sneaked past. Also found a cube, took it and it started a quest witch didn't want to do right at that time.
I did have some moments with the same guard. One time he came in a room and he didn't see me when i was RIGHT next to him, i got my weapons out in case he would spot me. But instead of turning to face me, he turned around the other way and went out of the room. I was looking at the screen shocked for like 5 minutes, it happened again in another room until the 3rd time, he spotted me so i killed him.
I must have some luck or something to avoid him twice right next to him.