Street crimes are the most prolific crimes and include burglary, robbery, assaults, and rape. This book's philosophy is that aggressive, on-scene investigations are the most effective in identifying suspects and obtaining the evidence necessary to obtain a conviction. The patrol officer is the first responder to a crime scene. The facts the officer gathers during the preliminary investigation provide the starting point to conduct a follow-up investigation. In the investigative process described in this book, the patrol officer and detectives locate sources of crime information such as radio calls, all-unit broadcasts, old crimes cases, and self-generated information. They identify the evidence or lead that will result in the identification of the suspects, such as nicknames, unique physical description, and license plate numbers. These leads are used to identify the suspect. The investigation obtains enough evidence to establish probable cause that the identified suspect committed the crime. Officers then locate and arrest the suspect. Investigators finish gathering evidence, such as admissions, clothing, and weapons that will convince the district attorney to seek a conviction. Among the techniques described by the author are photographic and "curbstone" lineups, interviewing victims and interrogating suspects to obtain vital information quickly, soliciting the help of fellow patrol officers, and how patrol officers work with detectives. Actual cases are profiled to illustrate investigative techniques.