For most police managers, administrative responsibilities usually consume most of their time, causing them to lose touch with the strategic and tactical aspects of criminal investigations. This routine changes, however, when a department becomes involved in a major case that requires an unusual commitment of departmental resources. Since mistakes in major investigations can have significant consequences, managers must be attentive to policies and tasks that increase the likelihood that the case will be resolved. The most costly mistakes tend to occur early in the investigation. At the first stage of an investigation, managers should ensure that the crime scene is secured, that sufficient personnel are deployed to perform required investigative tasks in a timely manner, that information is collected on what happened before investigators arrived, and that a canvass of the neighborhood of the crime scene is conducted. Appropriate command and investigative structure should be created, including the establishment of a command post relatively close to the scene of major investigative operations. Investigative principles are explained under the following instructions: "Be a supervisor;" "start with initial information;" "prioritize leads;" "verify everything;" "do it now;" "recognize the obvious;" and "avoid tunnel vision."