The Der Spiegel article mentions SD chief Colonel Engelke as a regular at the Madame Kleinknect's salon. He doesn't rate a Wikipedia entry, but there is a fascinating discussion thread about him on Axis History Forum, described as an apolitical forum for discussions on the Axis nations, as well as the First and Second World Wars. From information on the thread from three researchers, we can piece together a biography.
Friedrich Engelke, known as Fritz, was born in Hannover in 1900. He prospered as a merchant and textile trader. During the 1930s he joins the administrative division of the SS, or Schutzstaffel, the paramilitary organization run by Heinrich Himmler. In November 1940, Engelke is identified as an SS-Ustof, or second lieutenant, with the SS-Wirtschafts-Verwaltungshauptamt, SS-WVHA, the organization responsible for managing finances, supply systems and business projects for the SS, according to Wikipedia. In June 1944, he has the higher rank of SS-Stubaf, or brigade leader.
He was stationed in Paris and placed in charge of the Buying and Distributing Office of Stocks and Commodities--sort of like the chief purchasing agent. One commenter notes that "it seems that he was corrupt and managed to loot a considerable amount of French property!"
A person by the same name was held as a prisoner in Dachau by the SS in April 1945. It is uncertain if it is the same one. However, there is also a suggestion that another SS officer who may have been his brother, Johann Engelke, was investigated for an unspecified relationship and was subsequently transferred to a military unit and reported missing in action.
After the war, Friedrich Engelke was convicted and sentenced in absentia for War crimes by the French on June 13, 1951. It was reported by another poster that he was still alive and residing in Hannover as of 1975.