So, cracking someone's skull in multiple places requires a fair bit of violence, it's obviously not something self-inflicted, and we have these guys who had opportunity.

So why haven't some Minnesota prosecutor ordered them seized through whatever system exists for that-- whether it's an indictment or an arrest warrant or whatever? Isn't this kind of serious assault a crime where it's mandatory to prosecute, so that there isn't even any prosecutorial discretion?

Reasonable question but at least in my location the answer is obvious:

while there are legal barriers to my local PD/SD working with ice, LEO and local judicial folks fundamentally think of themselves on the same side as these folks.

That feels pretty trivially true: if you work in gov, especially at the violent tip of its local spear, you're going to go with that hierarchy over the folks you're ostensibly "serving".

I've never expected it to be otherwise, though as I get older I'm more comfortable understanding that they are complicit in making themselves less legitimate. At more and more points I feel more and more comfortable just thinking that the government doesn't have legitimate authority to do what they are trying to do.

I worked really hard on my brain to get it to not do that, but here we are.

I think they'll be too busy trying to figure out how to charge Mondragón with wilfully damaging an ICE agent's truncheon with his skull.