Police Forces

[Legbreaker]

Originally Posted by CDAT

...to just be left locked in there cells.

You may even find some family members or sympathetic and/or misguided people take over from the guards by supplying food and other necessities. They may not have the keys to open cells or the equipment to break them open, but...
In the case of family or friends, they may understand that opening the cells and releasing the prisoner(s) could be a very bad thing, but given their personal ties, leaving them to die isn't an option either.

Could be a bit of an adventure hook there. For example a person approaches PCs for help in getting somebody out because they're no longer able to feed them through the bars. Person tells PCs the prisoner is wrongfully imprisoned/victim of marauders or some other sob story (could be true, could be total fiction). PCs help and release a serial killer into the world and then have to deal with the consequences.