The piece alleged that Wal-Mart was paying bribes so it could build a store near the environmentally fragile and historic San Juan Teotihuacan pyramids.
"In response to this report, the New York Times reported that your company spokesman 'said that while executives in the United States were aware of the furor in Teotihuacan they did not know about the corruption allegations,'" the letter reads. "However documents obtained by our staffs from a confidential source indicate that you and other senior Wal-Mart officials were personally informed about these bribery allegations on multiple occasions."
At a meeting in New York last month, Duke declined to give details about the investigation.
Here's the letter, which includes emails allegedly sent to Wal-Mart executives concerning the scandal:
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