Of some critics' assertions that his source for the book had fabricated his story, Jonas told the publishers and Jonas that he was head of a Mossad hit team. Given the nature of intelligence and secret operations, Jonas acknowledged there was no sure way to determine whether his source was telling the truth, as governments do not like to confirm such material. But he had done considerable research, and said that he could confirm details at some of the places where his source had claimed to be operating.