Wal-Mart Stores is the subject of a whistleblower complaint for the second time in three weeks. A complaint filed Friday with the U.S. Labor Department asserts that Rickey Armstrong, a quality auditor in Wal-Mart’s Dallas Optical Laboratory, was fired by the retailing giant on March 12 in violation of Section 806 of The Sarbanes-Oxley Act of 2002.

The complaint asserts that in February and March of 2005, Armstrong made reports to Wal-Mart’s human resources organization and others within management of conduct that he “reasonably believed” to be in violation of federal law pertaining to fraud against the company’s shareholders. Wal-Mart responded by retaliating against Armstrong and terminating his employment, it adds.