During the interwar period, Mušicki served as an aide to King Alexander and Queen Maria. He joined the fascist Yugoslav National Movement (, Jugoslovenski narodni pokret, Zbor) following the king's assassination in 1934.
Between the wars, Mušicki worked closely with King Alexander and Queen Maria. After the king's murder in 1934, he became involved with the Yugoslav National Movement (Jugoslovenski narodni pokret, Zbor), a fascist organization.