By Se Young Lee SEOUL (Reuters) - Samsung Group said it will disband its corporate strategy office after a special prosecution probe ends, setting a timeline on a pledge to wind up a power center that has been criticized for its role in South Korea's graft scandal. The strategy office, comprising some 200 elite staff hand-picked from affiliates of the nation's top conglomerate, is the vehicle through which the founding Lee family makes key decisions such as restructuring and investments for new businesses, insiders and analysts say. It has been under intense scrutiny as the South Korean special prosecutor's office probed the smartphones-to-biopharmaceuticals business empire as part of a wider investigation into the scandal that threatens to permanently unseat President Park Geun-hye.