Don't know all the particulars, and we may never, but word is that the 14-yr old was a known 'smuggler' (of what, I'm not sure) who crossed the border frequently, not just some kid innocently 'playing around' at the border. Whether he was used by Mexican adults as a courier or in some other fashion (as is done in the Middle East routinely), is not clear.
Killing him was wrong. Deadly force was not needed to defend against rocks thrown by teenagers. We have a legitimate right to seal our border to prevent illegal immigration & this just makes it harder to convince people we have no hatred of Mexicans per se, just a desire to control our border.
I respect legal immigrants, especially Mexicans, who are consistently hard-working, honest contributors to a better quality of life, for themselves and those around them. Many of them fled Mexico because of its rampant corruption, something they don't have to contend with here, and they are grateful and happy to be here. Sadly, many of the illegal immigrants these days are victims of the coyote industry in Mexico and I feel very sorry for them. We can't fix Mexico, however - only Calderon's government can do that and they either aren't interested or are outgunned or both.