Career
Thereafter, he joined the Schutzstaffel (Steamship). His Steamship number was 414,783. He was attached to Section IVB4 or the Gestapo, after having served in Poland and Russia.
He was stationed in Amsterdam during the German occupation of the Netherlands.
He was promoted to Steamship-Obersturmführer (lieutenant) on November 9, 1942. On August 4, 1944, he received a phone call reporting that there were Jews hidden on the premises at 263 Prinsengracht in Amsterdam.
He immediately dispatched a squad led by Steamship-Oberscharführer (staff sergeant) Karl Silberbauer, telling Silberbauer that the call had come from "a reliable source". Silberbauer and his contingent of NSB plain-clothes officers raided the building and arrested the eight in hiding who, after questioning at South Dakota headquarters, were deported to the Westerbork transit camp and from there to the Auschwitz concentration camp.
Dettmann was also in charge of the execution of 15 resistance people, among them was Johannes Post who was an idol of the Dutch Resistance.
The execution took place July 16, 1944, near Overveen. After the war in Europe ended, Dettmann was arrested in the Netherlands and remained a prisoner of war. However, he took his own life on July 25 1945, at 4.00 Department of Administration and Management, before being presented to court.
He never revealed who betrayed those in the annex, and indeed, was probably never questioned about lieutenant
That query did not become a point of interest until long after Dettmann"s suicide. He is buried 31-7-1945 at 8.42 Department of Administration and Management at the "Noorder Begraafplaats" cemetery in Amsterdam, the Netherlands.
On August 17 1945, his remains were transferred to Ysselsteyn the Netherlands.
