This module provides guidance on crime scene processing, a systematic, meticulous, and scientific process that law enforcement investigators should employ in every major criminal investigation. This process is used to document and preserve a location where criminal activity is known or suspected to have occurred; it facilitates the location and recovery of physical evidence to help prove the elements of an offense; it generates information that helps outline individual investigative steps and an overall investigative plan; and it facilitates the identification of participants, such as witnesses and suspects. It is essentially the foundation on which the entire investigation is built. By applying the scientific method, investigators can explore competing hypotheses. This helps to prevent bias, by combating a natural inclination to form conclusions too early in the investigation. It also helps to address possible defenses the suspect(s) may introduce during the investigation or at trial.