Where is the Shadow Thief Cellar Key???

I an re playing BG2. Honestly this parts mostly make me wanna go play IWD or BG1 again because is too annoying. I an searching for this key for 2 hours. Every guide on google say nothing about it

http://www.sorcerers.net/Games/BG2/Walkthrough2/SoA/chapter-3/areas/docks-shadow-thief-guild-bodhi.php

http://www.sorcerers.net/Games/BG2/Walkthrough2/SoA/chapter-3/quests/bodhi-3-kill-aran-linvail.php

http://www.gamebanshee.com/baldursgateii/walkthrough/shadowthievesguild2.php

THIS IS ANNOYING AS HELL!!!! An door that any of my chars should be able to vaporize without any problem and i need to walk in circles all day because i can't foretell where is this dan key. Already looted every body that i saw on the thieves guilde. This is frustrating as hell.