Complex sentence: At the same time, Radek had supported the Warsaw opposition to the leadership of the SDKPiL (around Rosa Luxemburg and Leo Jogiches), and was expelled on charges of having formerly stolen clothes, books and money from party members.
Split into simpler sentences: At the same time, Radek had supported the Warsaw opposition to the leadership of the SDKPiL (around Rosa Luxemburg and Leo Jogiches). The SDKPiL expelled Radek on charges of having formerly stolen clothes, books and money from party members.