Two authorities (the head of the Institute of Police Science School of Law, University of Stockholm, and Chief Inspector of the New York City Police Department and Dean of the Police Academy) state that the book is intended ""primarily for policemen, detectives and other peace officers, for lawyers and students of criminal investigation."" But it is also a hobby book, a book for writers of detective fiction, for country officers. New scientific and virtually infallible methods for tracing evil deeds back to their perpetrators; chapters on tracing the fugitive, on identification by the Bertillon system, footprints, tooth, hair, blood, ears; chapters on tools, broken glass, firearms, ink. Practical study of the needs and equipment of a well equipped crime laboratory. Ten Thousand Public Enemies market will be to some extent interested.