There's an entire federal division on public corruption where eager young feds seek to take down public officials to make a name for themselves.

Sure, there's no one to watch the feds, but this isn't that, this is state law...

Technically there's a FISA court to oversee warrantless wiretapping, but they appear to be in the tank with the FBI.

I suspect the that while this typically would see no material remedy it’s so egregious, and exacerbated by the death of the newspaper co-owner as clear suffering, and so notorious on the world wide stage, something will be done to make an example of the police and judge at the federal level.

A big part of what makes this sort of small town corruption possible is that it's really hard to get people from outside the town to actually care. This story managed to get national attention so it's much more likely than usual to have something happen.

My cynicism encourages me to agree with you; however, I think it's worth considering how much political capital is created or conserved by 1) protecting the five-member police force and some random local magistrate vs. 2) taking a hardline stance against Corruption by sending the feds in and prosecuting everybody involved (even/especially if charges are dropped in a couple months)