The people Aaron informed on that the public doesn't know about had their cases wrapped up with the folks in that case(s) received their sentence. We may never definitively know who it was that he told on because those folks didn't take their case to trial. The gov't scared whoever it was enough for them to sign and not go to trial. On the indictment Aaron would be identifies only as "CI 1,2, 3 or 4"(confidential informant and if there is more than 1 CI whatever # he was assigned).
Defendants all have the right to face their accusers which is exactly what Aaron was in whoevers case he was used as the CI willing to testify against them and agreed to point the person out in open court. Many times rats aren't identified. We know when their sentences fall outside the sentencing guidelines. Its like the actor/rapper TI who was indicted for purchasing and possessing a machine gun and silencer. His guidelines, depending on what his criminal category was would've been at the absolute minimum of 10 years and much more likely to be 15 years. He agreed to testify against the person he put and proved to the satisfaction of the US Prosecutor was actually responsible for the machine gun and silencer. Someone had to do the time for those items. The poor sap that was indicted at some point for a machine gun and silencer took the deal for time that the gov't offered and opted to not go to trial and risk a much longer sentence if found guilty. Had that person taking his case to trial TI would've had to testify in court. Its a safe bet for TI and anyone in that position because chances are that guys do not go to trial.