Complex sentence: In 2017, the chapter at Auburn University was shut down after public concerning allegations led to a thorough investigation by the national office which determined the chapter was guilty of hazing, illicit drug use, and alcohol violations.
Split into simpler sentences: In 2017, the chapter at Auburn University was shut down after several serious allegations were made public about the behaviors of the chapter. As a result, the national office initiated a thorough investigation into the chapter which determined the chapter was guilty of hazing, illicit drug use, and alcohol violations.