Complex sentence: All were arrested, the books that were found were confiscated, and the nobles were then sent home with a warning not to continue, but Kim Beom-u was tortured, exiled, and finally executed since he was not of noble birth.
Split into simpler sentences: All were arrested, the books that were found were confiscated, and the nobles were then sent home with a warning not to continue. However, Kim Beom-u was tortured, exiled, and finally executed since he was not of noble birth.