The tone of Sleeping With the Devil is subjective. The author is writing about his own experiences and presenting his own opinions. He obtains much of his information from conversations with people and from intelligence sources. He analyzes the information and presents his conclusions. The problem is that there is no way for the reader to substantiate any of the information, such as the story about Adnan Khashoggi leaving a briefcase with one million dollars in cash at the San Clemente home of Richard Nixon several days after he is elected President.