Feet of Clay — Terry Pratchett

MURDER IN DISCWORLD

A killer is stalking Ankh-Morpork. A grim reaper who belongs to neither the Assassins' Guild nor the Thieves' Guild. A prowling perp who jauntily leaves behind corpses and strange-smelling tracks of curious white clay.

Commander Vimes of the Ankh-Morpork City Guard is determined to stop this unauthorized assassin, and he has hired a Dwarf to help him. With the assistance of the Corporal Cheery Littlebottom, Vimes and his men (and trolls and such) can get to the, well, bottom of anything.

Even when one of the victims is murdered with a loaf of her own Battle Bread (available in convenient throwing slices). Even when the investigation leads to an out-of-work golem, a vampire dragon and a vegetarian werewolf...