[1] Plietzsch was trained as an art historian in Berlin, where he worked for Wilhelm von Bode.
Later on, after the death of Hofstede de Groot he planned to compile his findings in a book, but was interrupted by WWII.
He was director and co-owner with Kurt Benedict of the Galerie van Diemen & Co. which had offices in Berlin, Amsterdam, The Hague, and NYC.
Reported to have been involved in the "confiscation of the Mannheimer Collection and the sale of the Mendelssohn Collection", he was taken into custody by the British and investigated by the Art Looting Investigation Unit in 1945–46, which also noted that Plietzsch advised Seyss-Inquart.
[5] Historian Jonathan Petropoulos notes that Plietzsch was "shrewd enough to burn all of his correspondance in his cellar" before the Nazis lost the war.