She would issue a confidential code to informants, who would turn around and redeem it at a local bank. Where the fraud came in is that she would duplicate the code for a friend, who would in turn rush to the bank to redeem it before the real tipster could. When the real tipsters would complain they didn't get paid, it was easy to tell her bosses that hey, we're dealing with the dregs of society, they're just trying to double dip on us. She had to know they'd eventually catch on.