With great concentration, you conjure up a gnoll disguise, allowing you to walk among the gnolls without interference. Listening to the little they speak of your language amongst themselves, you learn that they're raiding Sentinel Hill in order to solve their own problems as well. By the time you arrive at Sentinel Hill, you've figured out how to conjure a sort of pastry filled with drippings. It's far more nutritious than the refugees were expecting, and once the gnolls finish being surprised at the starchy nature of your fragrant concotion, they're quite satisfied as well. Even the murderer approaches you to confess that the murders were a shortsighted attempt to solve the source of Westfall's hunger problem, and now that you've satisfactorily done that, the murderer will go into a self-imposed exile.
It seems you had the real solution. If only the murderer had seen the plan...