Various, Trial of the Major War Criminals Before the International Military Tribunal…
“ Although, as Himmler put it, the SD was only the intelligence service of the SS during the years preceding the accession of the Nazis to power, it became a much more important organization promptly thereafter. It had been developed into such a powerful scientific espionage system under its chief, Reinhard Heydrich, that on 9 June 1934, just a few weeks before the bloody purge of the SA, it was made by decree of the Defendant Hess, the sole intelligence and counter-intelligence agency of the entire Nazi Party. ”
