Complex sentence: He was a top associate of President Thomas Sankara during the 1980s, and in October 1987 he led a coup d'état during which Sankara was killed; subsequently he introduced a policy of "rectification", overturning the Marxist policies pursued by Sankara.
Split into simpler sentences: He was a top associate of President Thomas Sankara during the 1980s, and in October 1987, he led a coup d'état during which Sankara was killed. Subsequently, he introduced a policy of "rectification", overturning the Marxist policies pursued by Sankara.