Walter Schellenberg, (1910-1952) an attorney who became a SS-Brigadefuehrer, heading the Sicherheitsdienst (SD) throughout WWII, which absorbed all other national foreign intelligence organizations of Nazi Germany. 
While imprisoned, he wrote his autobiography, The Labyrinth. He analyzed Germany's failure to integrate the counterintelligence and counterespionage functions, and attributed it part to Germany's not having a "Secret Service" tradition like that of the British Secret Intelligence Service. Commenting that his immediate supervisor, Reinhard Heydrich, played "divide and conquer" with the various security agencies, resulting in "overlapping bureaus and agencies, which resulted in duplication, waste, inefficacy, and the inevitable personal and professional jealousies. Finally, there was a drastic shortage of specially trained personnel."
It was reviewed in the U.S.Military Intelligence Professional Bulletin, and described as a useful addition to the literature of intelligence. 
He joined the SS in 1933, doing administrative work and lecturing to SS members. He moved to the SD the next year, and becae a headquarters legal assistant in 1936.
He was assigned to the Gestapo in August 1939 and put in charge of counterespionage. In 1941, he and his functions were transferred into the Political Intelligence Service, also known as the External SD, and became its department head in 1943.
In 1943, he was contacted by Martin Luther of the Reich Foreign Office, attempting to obtain SS assistance in supplanting Joachim von Ribbentrop as Foreign Minister. When Heinrich Himmler was informed, he ordered Luther's arrest and confinement in Sachsenhausen Concentration Camp, although Luther was released before the end of the war.
He testified against major war criminals at the International Military Tribunal (Nuremberg), especially Ernst Kaltenbrunner. In a later trial in the Ministries Case before the Nuremberg Military Tribunals, he received a six-year sentence; commuted before his death from liver disease. He received a light sentence in recognition both of his testimony, and his attempts, late in the war, to assist concentration camp prisoners. 
- Walter Schellenberg (1946), Affidavit of Walter Schellenberg, Nazi Conspiracy and Aggression, vol. VIII, U.S. Government Printing Office, Document UK-81, at 622-629
- Walter Schellenberg (2000), The Labyrinth: Memories of Walter Schellenberg, Hitler's Chief of Counterintelligence, Da Capo Press, p. 209
- James L. Mader (April-June 2004), "Review: The Labyrinth: Memories of Walter Schellenberg, Hitler's Chief of Counterintelligence", Military Intelligence Professional Bulletin