(I posted this as a response but I think it is worth it's own thread as I have seen a number of postings about writing to mexico)

Writing to the mexican government is a waste of time. They don't care about your letter.

Also at the same time you're directly identifying yourself to the mexican government. Should any hate speech laws get passed in the US, I'm sure the mexican consulate would be happy to have you arrested for a letter like that.

Write letters to the editor to newspapers, write to US officials, and write to companies about boycotting their products if they support the invasion (marketing to and/or hiring illegals, etc.). That is a much better use of your time and it will get results.

Just as an idea starter - why not write a letter to the editor and a letter to your Congressman and Senators about the Ramos and Compean case?