In a recent Miami Herald interview, former Mexican Foreign Minister Jorge Castañeda answered many questions. Two particular interesting bits:

Castañeda: There are not more people coming from Mexico than before; rather, it is that more people are staying in the United States, which gives the impression there are more, which is, I think, rather new.

Castañeda: I think [Mexico is] somewhat hypocritical in that we mistreat many Central American immigrants here. The difference is that most of the people who come to Mexico from Central and South America are on their way to the United States. They aren't here to find jobs. To a large extent, we are doing a little bit of the United States' dirty work for it. I don't agree with it, because I don't believe we should violate human rights in order to stop what the United States calls "OTM," or "other than Mexican," immigration. But unless it's part of an overall deal, as in comprehensive immigration reform, there's really no incentive to change. If there is an immigration agreement with Mexico, then there is incentive for Mexico to seal off its southern border in an honest, secure, humane way.