Wal-Mart investigated allegations of bribery among its Mexican executives in 2005, but then shut it down, without notifying Mexican or U.S. authorities, and without disciplining any of the executives in charge. In response to continuing criticism, Wal-Mart then put in charge a lawyer who was himself alleged to have authorized the bribes, accepted his results and again thought they’d put the thing behind them.
One of the head guys was assigned to investigate cleared everyone "because none of the people he interviewed about the matter mentiond they had paid bribes." Well that was proof, right??
Having lived in central Mexico for the last seven years, I can tell you this is how business is done in Mexico. Good luck getting anything approved or built without bribes.