What is a control to compensate for a programmer having access to accounts payable production data?

Having the accounts payable supervisor match all checks (cheques) to approved invoices.

To ensure that the programmer could not have a check (cheque) generated, it would be necessary for someone to confirm all of the checks (cheques) generated by the system. Range and logic checks could easily be bypassed by a programmer, since they are privy to the controls that have been built into the system. The review of the accounts payable reports by data entry would only identify changes that might have been made to the data input. It would not identify information that might have been changed on the master files. Reviewing reports for checks (cheques) over a certain amount would not allow for the identification of any unauthorized, low-value checks (cheques) or catch alterations to the actual checks (cheques) themselves.