Complex sentence: Payne co-wrote a series of articles about the Symbionese Liberation Army and the kidnapping of Patty Hearst; it became the basis of his next book, "The Life and Death of the SLA".
Split into simpler sentences: Payne co-wrote a series of articles about the Symbionese Liberation Army and the kidnapping of Patty Hearst. These became the basis of his next book, "The Life and Death of the SLA".