It is well known that plea bargaining as such was not provided for by the Nuremberg Charter, nor is there any instance of plea bargaining in the trials conducted by the occupation tribunals under Control Council Law no. 10. However, as shown in this paper, in connection with war crimes committed in the Second World War, there were negotiations between the Allies and persons who could have potentially been charged with war crimes. The case of Captain Guido Zimmer is exemplary in this respect. He could have been accused of war crimes and tried by a competent tribunal: instead, since he cooperated with the Allies (in particular with US intelligence), the decision not to prosecute him was taken.