Complex sentence: He is confronted by his editors about a story he has written and has featured on the cover of the "New York Times Magazine", who accuse him of using a composite character as the focus of his story, a violation of basic reporting principles.
Split into simpler sentences: He is confronted by his editors about a story he has written and has featured on the cover of the "New York Times Magazine". They accuse him of using a composite character as the focus of his story, a violation of basic reporting principles.