Walmart acknowledged Sunday that it is investigating allegations that its Mexico subsidiary used bribes to get building permits quickly to achieve rapid growth and remain ahead of its competitors. The New York Times reported Saturday that the big-box giant began a probe into a former Walmart de Mexico employee’s accusations only after as much as $24 million had already changed hands, and that it tried to hush up the scandal. In a report obtained by The Times, the company’s lead investigator said, “There is reasonable suspicion to believe that Mexican and USA laws have been violated.”