A couple of things...

1. Someone can correct me if I'm wrong but, as I stated earlier, USAT would have no dog in this fight. IMCoz is not a USAT sanctioned event, since Mexico isn't part of the USA.
2. You're in a rock and a hard place when it comes to law enforcement for several reasons. I am an FBI Agent (I can't help but not say that like Keanu Reeves in Point Break) so I feel I can intelligently address this part of the equation.
- It was in a foreign country. That's by far the biggest hurdle you'll face. We could debate some possible semantics about where the fabricated documents were made (probably in the USA) but the best venue option for prosecution is Mexico. That's where the race was held, that's where they stole your identity, that's the country they entered while carrying false identification documents, etc.
- Mexico won't do a damn thing about it.
- Even if you could overcome the foreign country venue issue (which you probably cannot) and establish some kind of venue in the USA, there's isn't a federal law enforcement agency or US Attorney's Office that will investigate it. It's just not a big enough deal to warrant the use of federal resources. That's just the reality. Federal criminal fraud prosecution really needs the following ingredients: a violation of a US federal crime as defined by some Title 18 USC statute, a victim, a loss, and that it meets the threshold limits of the district. I've had million dollar fraud cases turned down because there were bigger cases that had to be prioritized. My district is much larger than the Eastern District but the loss in this case is still just $600 or so.
- I'm not exactly sure what local/state law enforcement could do. They're even more hamstrung by the venue issue but I could see charging them with some minor theft charge. The problem with that is you had no intention on going to the race so it could be argued it was "victimless."

Best of luck. Those people deserve whatever is coming to them if all this is true.