Complex sentence: Despite the verdict, the Tongan justice system was reluctant to release Priven, but after receiving a letter from the U.S. State Department promising that he would be involuntarily committed to a mental hospital, handed him over to the U.S. government.
Split into simpler sentences: Despite the verdict, the Tongan justice system was reluctant to release Priven. After receiving a letter from the U.S. State Department promising that he would be involuntarily committed to a mental hospital, Tonga handed him over to the U.S. government.