The truth can really hurt, as Staples Inc. learned the hard way after mass e-mailing its employees to inform them that a co-worker had been fired for breaching the company’s travel and expense policies. An expense claim of $1,129 for a Big Mac was one tip-off that something was seriously wrong with Alan S. Noonan’s expense reports.

The traveling salesman admitted to auditors for the Boston-based office products giant that he had been careless. He explained he had inadvertently misplaced the decimal point on the $11.29 meal he bought at the airport. But other anomalies in his expense claims convinced a special forensics team that Noonan had deliberately falsified his expense reports.