I have found and killed this guy twice now (trying to obtain his mask and end quest) and both times he does not drop it....there is nothing in his ash pile but gold and ectoplasm......isn't he supposed to drop it? Is it somewhere else?
There are several priests in there. You only get it if your on the quest and he was wearing it when I got mine. Then again you may have to go out front and kill the imposter guy. I can't remember exactly but I had some trouble finding it also.