"In the field of counterintelligence, a double agent (also double secret agent) is an employee of a secret intelligence service, whose primary purpose is to spy on a different target organization, but who, in fact, is a member of the target organization.Double agentry may be practiced by spies of the target organization who infiltrate the controlling organization, or may result from the turning (switching sides) of previously loyal agents of the controlling organization by the target."@en . . .