They even try to appeal to your emotion, in this case anti-aboriginal prejudices (that I agree does exist, but I do not agree that it is a significant factor here).

I agree with you there. Personally I think the most significant factor is that Feds were killed (and they were going to get someone).

Fabricating evidence in a legal case and proceeding.

This does occur and I think does raise a point from the Wikipedia article about the original trial:

Unlike the juries in similar prosecutions against AIM leaders at the time, the Fargo jury were not allowed to hear about other cases in which the FBI had been rebuked for tampering with evidence and witnesses