The accuracy of information obtained from witnesses will depend on their ability to observe, comprehend, remember, and express facts, as well as on obstacles to perception such as external conditions, insufficient attention, and physical and mental/psychological limitations. To avoid later legal problems, composite artists should adhere to departmental rules and regulations and should follow court guidelines for avoiding suggestivity in communications between the witness and artist or among witnesses. In opening lines of communication with the witness and refreshing witness memory, visual stimuli such as arrest photographs and mug shots may prove helpful. Witnesses should know what is expected of them and should be treated with patience, courtesy, and understanding. While the standard police interview can produce a quantity of information and detail, it may discomfort or intimidate the witness. The cognitive interview has been found to enhance more accurate memory retrieval in that the witnesses follow their own thoughts and recount the incident in their own words. Interview sessions should be loose, general, and leisurely. The witness is asked to restate the context, tell everything, recall the event in a different order, and report events from the perspectives of others who were present. In some cases, a combination of traditional and cognitive interview techniques may be preferable. Steps for interviewing and evaluating single and multiple witnesses are provided. 17 references.