i was sent on a quest to find him , i found , went back and was told he still wanted proof so i killed the little punk (which by the way took me about three hours) took his staff back and still no go somebody help me before i go insane

You have to find his treasure, which is on the other side of the Anephas Shrine.

(HINT: you have to find Kerah's area in the Shrine and the hidden lake to find the Leprechaun Treasure. In the chest you'll find an amulet called the Stone of Clover. Bring that back to the Thieves guild...that's what he's looking for.)

-Sazerac

thanks, i worked it out and noticed a bug at the same time, in the thieves guild, i f u click on all thieve guild membersseveral times over and over, he repeatedly awards u 5000 experience points. thx again.