Complex sentence: Following the murder of Aubrey, people in the area quickly suspected that the Ho-Chunk were involved which exacerbated the fear that more from the Ho-Chunk Nation were set to join Chief Black Hawk's band against the white settlers in Michigan Territory and Illinois.
Split into simpler sentences: Following the murder of Aubrey, people in the area quickly suspected that the Ho-Chunk were involved. This exacerbated the fear that more from the Ho-Chunk Nation were set to join Chief Black Hawk's band against the white settlers in Michigan Territory and Illinois.