Generally, police forces separate from the local military or militia do not exist.
In the countryside, the men-at-arms of local nobles enforce the law, while the city watchmen do this in urban areas.
Executioners, however, are a distinct professional group. Execution, torture and mutilation are seen as a very unsavoury profession, and executioners are shunned. Some may hold the job secretly, in in some areas, there is a custom that a criminal condemned to death may be spared if he becomes the new executioner, after the previous one has died.
Beyond this, there are also various forms of state investigators, known as coroners in Clemencia and the Free Kingdoms, and as justicars in the Confederation and the Cargan Empire. These are of high status and are tasked with upholding the state law and seeing that enough amercements are collected...