Huppenkothen attended school in Opladen and studied Law and Political Science at the University of Cologne and University of Düsseldorf and then qualified as a lawyer. On May 1, 1933, he joined the Nazi Party and the Allgemeine SS. Unable to find employment in government service he joined the SD (the intelligence service of the SS) in Düsseldorf. After the invasion of Poland he was commander of the Security Police and the SD in Kraków, then in February 1940 he was posted Lublin as head of the Gestapo. From July 1941 he was appointed to the Reich Security Main Office in Berlin with the rank of Sturmbannführer (Major) in charge of a Gestapo Unit dealing with reactionaries and liberals, as the successor to Walter Schellenberg. After the dismissal of Wilhelm Canaris he attended a meeting in March 1944 that established a unified intelligence service.
As an SS Standartenführer (Colonel) he was appointed the prosecutor of the SS and police court in Munich. On April 6, 1945, he prosecuted Hans von Dohnanyi in Sachsenhausen concentration camp while the defendant lay semi-conscious on a stretcher having contracted a serious infection and the proceedings ended with him being condemned to death by Sturmbannführer Otto Thorbeck.
On April 8, 1945, under orders from Ernst Kaltenbrunner, he was the prosecutor at a drumhead court-martial presided over by Otto Thorbeck without witnesses, records of proceedings or a defence in Flossenbürg concentration camp. It condemned Dietrich Bonhoeffer, General Hans Oster, Army chief judge Dr. Karl Sack, Captain Ludwig Gehre and Admiral Wilhelm Canaris to death. They were all hanged on April 9, two weeks before the United States Army liberated the camp. Thorbeck later testified that the conspiracy trials lasted three hours under Huppenkothen's direction and that he shouted the accusation at them, then permitted a brief answer period before the death sentence was imposed and the prisoners were executed the following day.
He was captured at Gmunden on April 26, 1945. After the war Huppenkothen was interned by the Americans and worked for the Counterintelligence Corps of the US Army until 1949. He was tried in West Germany in the 1950s and sentenced to seven years' imprisonment, but was acquitted of murder. That acquittal was, and remains, controversial.
- Walter Huppenkothen at munzinger.de (German language) Retrieved 22 September 2013
- Peter Hoffman (1996). The History of the German Resistance, 1933–1945. McGill-Queen’s Press. ISBN 0-77-3515313.
- Time-Hitler's Advocate
- See the article on Otto Thorbeck.