I am not sure if they do locally in Jones county, but the Des Moines Historical Society does have prison records for Anamosa. I've used them before to look up a person serving in 1909.
You have to look up the book, and request it be pulled from the collection or at least I did. I'm not sure; it will give you a lot of information. My record only was a single entry line: name, date, crime, how long they served. But there could be more in them.