Complex sentence: As she digs further, local authorities stonewall her efforts but Sonja learned that there had been eight concentration camps in the area and that all the Jews were forced out of the town and their property confiscated.
Split into simpler sentences: As she digs further, local authorities stonewall her efforts. Sonja persists and learns that there had been eight concentration camps in the area and that all the Jews were forced out of the town and had their property confiscated.