The introductory section outlines the theory of investigation and defines the investigator's three 'tools'--information, interrogation, and instrumentation. The role of the investigator's notebook and the importance of report writing are also described. The second section presents in detail an investigation's initial steps, including crime scene search, sketches and photography, and the collection and handling of evidence. Sources of information and methods for obtaining it are described in chapters on interviews, interrogations, admissions and confessions, informants, missing persons, surveillance, undercover assignment, and related topics. Successive chapters apply these search and evidence collection procedures to investigations of specific offenses: arson, narcotics violations, sex offenses, theft offenses, forgery, homicide, and criminal explosions. Two chapters on courtroom procedures discuss the rules of evidence, the principles of proof, and the presentation of findings. Chapters on methods of identification explain observation and description, identification by witnesses, fingerprints, fingerprint classification, laundry and drycleaning marks, casting and molding, and various impressions. A final section discusses the state of the art of specialized scientific methods. Information is provided on stains, traces, and chemical analysis; firearms; tests for intoxication; tracing materials and detective dyes; hairs and fibers; invisible radiation; and documentary evidence. Photographs, illustrations, reading lists for each chapter, an index, and appendixes discussing white-collar crime, arrest procedures, search and seizure procedures, and suggestions for law enforcement agencies sending evidence to the FBI laboratory are included.