I don't think that AIM as an organization did this.
I think the person who did this is really a predator, but he doesn't like to think that about himself; so he uses AIM ideology to give a veneer of justification to this crime.
These old AIM activists live to discredit the FBI. That is what they do. If you can discredit law enforcement, you can take over the town or the reservation.
A lot of AIM people were criminals--burglars and drug dealers--who wanted the FBI (which investigates serious crimes on reservations) to be discredited so the Indians wouldn't come to the FBI for help or to report crimes.
Ah! I see now. Thanks for clearing it up.