Complex sentence: The next morning the police, having learned of Mike's affair with Joe's wife, decide Joe must have killed Mike for revenge and move to arrest him, but Milo, Marcone's top henchman, captures Joe first.
Split into simpler sentences: The next morning, the police, having learned of Mike's affair with Joe's wife, decide Joe must have killed Mike for revenge and move to arrest him. But Milo, Marcone's top henchman, captures Joe first.