Following the development of a theory of defense for the case, an investigation plan should be composed and implemented. Components of such a plan are an initial evaluation of the facts and issues of the case, the elements of proof the prosecution needs to prove the case, sources and location of information, resources and methods for the investigation, evaluation and preparation of evidence for presentation, and the management of the investigation and allocation of available resources. This article focuses on general aspects of the investigation and information acquisition. After listing the basic skills needed to investigate a criminal case, the article suggests nonstatutory sources of information and outlines a "systematic approach" to be used in every case. Such an approach asks questions related to who, what, where, when, how, why, with what, with whom, and how much. A discussion of other sources of information focuses on statutes, police documentary and physical evidence reports, identification, and scientific or forensic evidence. Other topics considered are the evaluation of victims and witnesses, preparation for trial, and plea negotiations. Appended detailed information.