C is an accounts clerKwho is supposed to sign each invoice as evidence that she...

D reviewed a sample of invoices for purchases of plant and equipment and found that C had not signed them C explained that she believed that those were authonsed by someone else although the accounts manual indicates that it was her responsibility

asked C a series of open-ended questions about the operation of the purchases system She did not mention anything about detailed checks of invoices against documents

D examined a sample of invoices to make sure that they had been signed by C AH had been signed

selected a sample of purchase invoices and compared each to the supporting documents that C is supposed to review Every one of D's invoices was supported by the related documents

D worked at a spare desk in the accounts department and quietly watched C without telling her She checked every invoice carefully while D was present