Your case officer will be one of the regular prison officers in your unit (sometimes called a “CO”, for “Corrections Officer”). A case officer will usually be responsible for supervising the management plan of a number of prisoners in the unit.
You’ll find it very helpful for your time in prison if you get along with your case officer. They’ll be your contact point for dealing with your case manager if you have any problems you want your case manager to know about or if there’s something you need to do.