For our first MuckReads podcast of 2013, we invited New York Times reporter David Barstow to talk to our editor Steve Engelberg about his investigation into how Wal-Mart used bribery to expand their business operations in Mexico.

Barstow and Engelberg talk about how the investigation got started, how he proved the validity of the information he received, why Mexico's FOIA/public records law was very helpful, the impact the reports have already had and ultimately, why looking into foreign bribery was important.

When asked how this investigation compares to some of the other Pulitzer Prize-winning work he's done, Barstow said, "This one had the highest degree of difficulty I think of any story I've ever done. Because it required, number one, penetrating to the highest reaches of a major corporation which is difficult to do in and of itself. But then it takes the added complexity of trying to understand a company's operations in a place like Mexico where the rules are incredibly complicated. You have to understand and learn everything that goes into the permitting process for a new Sam's Club or a Wal-Mart. We're talking 15 to 20 permits per store issued by different agencies and different bureaucracies and tearing all of that apart in a place like Mexico and then lining it up against the reporting and the documentation that we're prying loose from the bowels of Wal-Mart de Mexico is a really unbelievable endeavor. At this point, I'm sure I've looked at well over 100,000 pieces of paper for this line of reporting. And so I think, in terms of degree of difficulty, it's the most difficult thing I've ever taken on."