The special considerations which must be given to the collection and handling of physical evidence from the scene of a crime for a forensic laboratory are presented. Specifically covered are the handling of physical evidence from criminal acts which violate those jurisdictions comprising an important segment of the responsibilities of the Bureau of Alcohol, Tobacco and Firearms in the U.S. Treasury Department. Many of the unique characteristics of this unusual type of sampling are discussed, particularly those aspects differing markedly from the more routine types of chemical sampling. Topics covered in detail include the following: the selection of materials of possible evidential value; the process of collecting and gathering such items of interest; the importance of marking and labeling properly; the packaging of these materials; their preservation; the proper transmission to the forensic laboratory; and the associated legal requirements which must be adhered to throughout this procedure.