it does not appear to me that you have done anything "wrong", rather, law enforcement may just not be able to discern that you are credible. You should consider exploring all avenues: local police, sheriff, state attorney general, and the feds--including homeland security, FBI, even ATF. The biggest obstacle is getting someone to listen.
That said, anyone who you have contact with is going to have very limited time, so you have to make the explanation very simple... if you can't explain the entire story and the evidence in 1/2 of a page or two paragraphs, the chances are that it's not going to be read.
The next consideration is to bring a civil suit against the boys. If you can prove your case in a civil arena, law enforcement is more likely to think that there's a case there for a criminal prosecution and less likely to be ignore what's happened.
The last thing that I might suggest is to go to your local district attorney's office and ask to speak with a prosecutor. Best of luck.
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