Complex sentence: Müller, a merchant by profession, joined the SS in October 1933 (member no.179,667), after the "Machtergreifung", and the Nazi Party on 1 May 1937 (member no.4,486,232).
Split into simpler sentences: Müller, a merchant by profession, joined the SS in October 1933 (member no.179,667), after the "Machtergreifung". He then joined the Nazi Party on 1 May 1937 (member no.4,486,232).