To help police investigators develop skills that will improve the low conviction rate for rape cases, this manual stresses an overall investigative strategy based on establishment of each element of the crime of rape. Analysis of data from large and small police departments across the United States shows that fewer than 3% of the crimes reported as rape result in a conviction; many cases are not filed or are plea bargained to a lesser offense because of insufficient evidence. This manual focuses on a step-by-step development of evidence through interviews with the victim, physical and medical evidence of force, crime scene evidence, interviews with witnesses, and use of third party reports such as local rape crisis lines or victim service organizations. Establishing a suspect, confirming the identification of arrestees, and collecting corroborating evidence are discussed. Special attention is given to particular problems of rape investigation, such as the need for establishing lack of consent when the victim knows the assailant. In addition, crime scene evidence and medical evidence of particular value in proving force are recommended. (Author)