The most important data set in the analysis was provided by the banks which had been defrauded. Access to this data was gained through participant observation in a specialized economic crime investigative unit. In February 1978, a Canadian bank mounted a check guarantee program that evolved over 2 years into a policy that permitted all credit card holders, whether or not they were customers of the bank from which they drew their checks, to cash any checks they wished up to $500 per day. The fraud involved using stolen credit cards to cash checks (either stolen or obtained through the illicit opening of an account) in a maximum number of different bank branches in the shortest time possible. Urban areas were used to decrease the time required to travel from one bank branch to another. The crime wave was fueled by the crime opportunity presented by the bank policy, and it ended with the bank's decision in May 1981 to lower the daily withdrawal limit from $500 to $100. The crime opportunity spawned interconnected crimes that included credit card theft, check theft, bank account openings under false pretenses, and related quantity frauds that depended on a complex fencing market. The study indicates that criminal behavior is stimulated by situational circumstances and opportunities that often require a series of interconnected crimes. 16 references.