Didrikson Rubin, the auditor of Red Barn Farm Equipment, was verifying cash payments to vendors for the past several months. She noticed that several checks had been paid to a specific vendor, but she couldn't find a record of the transactions in the computerized system. Didrikson suspects that an employee is issuing checks to a fictitious "vendor" and then deleting the transactions from the computerized system. How might Didrikson investigate the suspected fraud?