Police patrols should become familiar with all aspects of white-collar crime since they are in an excellent position to gather useful information through conversations with local citizens and knowledge of a neighborhood's activity patterns. 'Paperhanging,' the passing of bad checks, is the Nation's fastest growing crime. Patrol officers can make the public aware of this crime, educate business owners in prevention tactics, and urge the precinct captain to keep a list of bad check passers. Items that should be covered in a public information campaign are listed. Because patrol officers are usually first on the scene of a crime, they should record all details even if some appear irrelevant. Informants are important information sources on white-collar offenses, and a registration filing system on these individuals should be reviewed to detect operating patterns in an area. Patrol officers need to be knowledgeable about the care, handling, and evidential value of all documents. Modern technology has been able to restore many documents which appear damaged, such as ones charred by fire. Other types of evidence which have been useful in investigations include stamps on envelopes and altered checks. Techniques for salvaging water soaked papers and obtain writing samples which are admissible as evidence are explained. Finally, the article presents a method for organizing all information collected by a patrol officer into a coherent chronological account accompanied by line analysis charts which depict relationships between persons and events where time sequences are not important. This approach is demonstrated by an investigation into a series of break-ins into retail appliance and stereo stores. Flow charts are included.