Instructions
Construct a Guard Post. Guards round up criminals, placing them in cells and removing them from the population. Unfortunately, convicts take up a population spot in your kingdom that might otherwise contain useful citizens able to perform tasks for the kingdom.
Build a Courthouse. The courts try criminals and either return them to the active, honest populace or to the cells.
Add a Torturer's Guild to your kingdom. This guild operates various rehabilitation devices which bring convicts back to the straight and narrow path.
Build punishment devices. These devices range from stocks -- which take up to two years to rehabilitate criminals -- to gallows and chopping blocks for immediate executions. New citizens replace executed criminals as soon as the punishment is over.