At the beginning of 1930, Hayn joined the
Nazi Party (membership number 211,251). As a close friend of
Ernst Röhm, Hayn decided to make a career in the
Sturmabteilung (SA), the Nazi
paramilitary formation, which Röhm headed as SA-
Stabschef. Röhm was a known homosexual and he "surrounded himself with youths whom he chose for their physical beauty and overt homosexuality … handsome, fair-haired, blue-eyed, young 'Aryan' men" including Hayn. Following the
Stennes Revolt, a mutiny that broke out on 31 March 1931 by SA formations in
Berlin against the Party leadership, Hayn was selected as the acting leader of the Silesian SA
Gausturm, replacing the previous commander who had supported the revolt. In June 1931,
Edmund Heines took over the leadership of the Silesian SA from Hayn, which at that time was upgraded from a
Gausturm to an SA-
Gruppe. Hayn was appointed chief of staff of the newly created and thus, after Heines, the second highest SA official in Silesia. He initially was named in an acting capacity but received a permanent appointment on 14 October 1931. Shortly thereafter, he was promoted to the rank of SA-
Oberführer in December 1931. On 15 December 1932, Hayn was transferred to the field command of
Führer of the SA-
Untergruppe Mittelschlesien-Süd. The previous leader, , had fled to Italy to escape arrest for his involvement in a series of terrorist bomb attacks, and the post had fallen vacant. On 1 July 1933, Hayn was appointed as the successor to SA-
Gruppenführer Georg von Detten as
Führer of the SA-
Gruppe Sachsen, commanding all the SA units in the state of
Saxony with his headquarters in
Dresden. He was also promoted to the rank of SA-
Gruppenführer. In addition to his duties in the SA, Hayn also pursued a political career in the Nazi Party. In the
July 1932 parliamentary election, Hayn was elected to the
Reichstag as a Nazi deputy from electoral constituency 7 (
Breslau) and was reelected in November 1932 and March 1933. At the
November 1933 election, he switched to constituency 28 (
Dresden–Bautzen) in Saxony, which he would represent until his death the following June. == Arrest and death ==