Dr. Siegfried Seidl [* 24 August 1911 in Tulln, Austria – † 4 February 1947 in Vienna, Austria] was SS Hauptsturmfuehrer and the commander of Theresienstadt.
In 1930 he quit law school and joined the Austrian NSDAP, and in 1932 he enlisted in the SS. During the 1930s he was active in the illegal movement.
After the Anschluss his career progressed quickly. At the end of 1939 Seidl became Inspector of the Security police (Sicherheitspolizei – Sipo) and Security service (Sicherheitsdienstdienst – SD) in Vienna. Shortly afterwards, in January 1940 he was transferred to department IVB4 of the RSHA headed by Adolf Eichmann (Reichssicherheitshauptamt -Reich Main Security Office). He was assigned to the SD regional headquarters in Posen (Poznan) and was a member of the Umwandererzentralstelle (Central Emigration Office) in Lodz, where he participated in the expulsion of Poles and Jews to the General government (Generalgouvernement).
In the same year he received his doctoral degree. He had resumed his studies in 1935. In mid-1941 Seidl was sent to Maribor, Lower Styria, where he was in charge of resettling the Slovenes.
On October 30, 1941, by now an SS Obersturmfuehrer, Seidl was ordered by Adolf Eichmann to set up a camp in Theresienstadt. He was Theresienstadt’s commander from November 1941 until July 1943. Seidl gave his orders orally to the Jewish council (Ältestenra) or to the ghetto guards. He implemented strict rules in the camp, imposed arbitrarily harsh prison sentences, or beatings, and had prisoners executed. During his command thousands suffered and died. In 1942 he was promoted to rank of SS- Hauptsturmfuehrer.
On 6 July, 1943 he was posted at Bergen-Belsen concentration camp, where he was in charge of Jewish prisoners with foreign citizenship. They were used in prisoner exchanges for Germans detained by the Allies
Later, he was sent to Mauthausen concentration camp to prepare the deportation of Hungarian Jews. In April 1944 he traveled through Hungary with the Eichmann commando to register Jews and confiscate their property.
From September 1944 on, he served as deputy commander of the SS special (SS-Sondereinsatzkommando) unit in Vienna, and oversaw the forced labor camps in Vienna and Lower Austria, where Hungarian Jews were imprisoned. After the war he went into hiding and assumed a false identity, but was arrested on 30 July 1945. In fall 1946 he was put on trial in Vienna, sentenced to death. He was executed in February 1947.