Complex sentence: He was captured by Auror Alastor Moody after the fall of Lord Voldemort; the Ministry of Magic released him from Azkaban in exchange for the names of other Death Eaters.
Split into simpler sentences: He was captured by Auror Alastor Moody after the fall of Lord Voldemort. Later, the Ministry of Magic released him from Azkaban in exchange for the names of other Death Eaters.