I've read a lot of spy novels.

Case Officer
The relationship between Case Officer and agent is very much akin to that of a psychiatrist and patient, because very often the person willing to become involved in espionage and the betrayal of his country, is someone with emotional problems, or may develop serious emotional problems from the stress of the work. The Case Officer is the complete intelligence professional in the operational field, always cool, level headed, in control of his emotions. Always ready to deal with a crisis, be it personal or imagined, or of the dreaded breach of security protocol type, sloppiness, laziness, stupidity, lack of motivation, carelessness. The Case Officer must constantly be looking after these concerns and be ready to mentor and exhort the bedraggled agent to carry on.
The term "agent" refers to "one who acts on behalf of another", the "another", in this case being an organization or government. Agents can be either witting or unwitting. They can also by willing of unwilling. Agents are almost always a foreign national who is under the direction of an agent handler or controller. In the case of the U.S. Central Intelligence Agency, this handler is known as a Case Officer.

http://www.conservapedia.com/Glossary_of_espionage_terms

Case Officer: a CIA officer that recruits and runs agents

http://www.geocities.com/operations_directorate_imf/Glossary...

case officer - An operations officer serving as an official staffer of an intelligence service.
http://themasterofdisguise.com/glossary.html

Agent handler is a generic term common to many intelligence organizations which can be applied to Case Officers, those who aspire to be Case officers, "controllers", contacts, couriers and other assorted trainees.