All intelligence sources have their peculiar merits and their peculiar blind spots; not one tells the whole story alone. Prisoner of War Intelligence is peculiarly strong in telling you what and how things are done by those who do them, while it illuminates the blind spots of other sources.
What men make good interrogators?… one would look first for a speculative mind unbound by preconceived notions and firmness of judgement in distinguishing means from ends.