Wait, Leonard Peltier is still alive, and still in prison?
Most people who have vaguely followed him over the years probably don't know that.
The big issue in the Leonard Peltier case, aside from his supposed guilt or innocence in the killing, is why would it be illegal for Natives to shoot people who are aggressively pursuing them. They were on Native land. A group of two FBI agents in an unmarked car went onto Native land and aggressively pursued some Natives who did not know why they were being pursued. The most basic common sense would be to shoot the agents. Who would argue against that?
There have been a lot of cases in the United States where police and other agents commit crimes, such as aggressively pursuing people, and the response is to kill those police or agents. Then a fake scenario is fed to the media suggesting that the police/agents were doing something legitimate but were 'attacked'.
A badge is not a license to attack the vulnerable, and, more importantly, a badge does not make a person bulletproof.
The United States had committed so much egregious misconduct in that area, for many decades, and that misconduct was ongoing at that time, so that any sensible Native in that region would consider government agents as hostile enemies, which they obviously were, and are.
Whether or not the killers knew initially that the two were FBI agents, once they realized that they were outside government agents there to harass or attack them, killing them was proper. What else should they do?
A big part of the U.S. assimilation strategy against Aboriginal Americans has been to fracture them into weaker and weaker groups which are further and further from traditional.
First their languages and traditions are taken, so they have to speak the language of the colonizer and can't remember who they are.
Then they are mixed with colonizers, through rape and other forced assimilation techniques, so that no man knows which male lineage he comes from, and no woman knows which female lineage she comes from. Few Natives know for sure if their root lineage is white or Native.
By the time Leonard Peltier hit the headlines in the 1970s https://en.wikipedia.org/wiki/Leonard_Peltier there were large groups of 'white Natives' overtly working for the U.S. government, and passing themselves off as 'Native leadership'.
One of the hidden tools of colonization is the evolution of the motives of the colonizers.
1) Initially the goal is overtly to get land. Colonizers take as much land as quickly as possible then move to the next phase.
2) Once the victims perceive a threat, it becomes important to create distractions. At this point there are coercive negotiations. 'We could take all your land, but we are good colonizers, so we will leave you a bit.'
3) On and on the ruse evolves until you get to where the U.S. is now. Yet another generation of enforcers is being raised to believe the stupidity that 'Now is different, we are all one happy nation, etc etc'. the 'standard' Bureau of Indian Affairs or FBI agent today passes for progressive. They 'support' Native rights except for the part about giving any land back. They know original social structures that Indians used in the past no longer exist, and that Natives have been forced into dependency on the U.S., so there is little chance of any surviving tribes getting back on their feet without a lot of help or weapons.