I think he doesn't want to know where to get the Chief's skin, but where to get the skins the Chief wanted back from the witches. In that case, go down the stairs at the bottom of the tower (south). Jump down the ledge and go to the right (east). I'm not exactly sure where, but there's a secret passage somewhere in the southeast quarter of the map. After you go through it, you'll be in a cave with a bunch of boulders and three ghosts. Kill the ghosts and push the boulders arounds so you can leave to the northeast. Got through the door in the south wall, fight the ghost, and solve the puzzle of the braziers. I you want the solution, I'll put it at the bottom as a spoiler. Anyways, in the next room you are teleported to a ledge with four boxes and the pelts are in one. To get out, jump down or walk around the ledge, fight some rats, and then wander towards the northeast till you hit places you've already been. To get out again, you'll have to pull a lever in a room off of a hallway where the ogres are.
SPOILER!!!
To solve the puzzle, you need to light all four braziers by stepping on maps. First open the door at the south, then step on the mats in this order. Top, left, right, bottom. All braziers should now be lit and the gate will open when you step on the middle tile.