After the revelations of the last episode, we know there's a secret organization within the police forces that protect itself.

This makes me believe all the suspects of PJ's list who work or worked for a police organization is involved in this secret organization, that includes Bertram, Sheriff McAllister, Smith, Haffner and maybe Partrige too.

I believe RJ is not the head of that organization, although he knows it and knows enough about it to make it go bust. He just exchanges his silence in exchange of protection for his own crimes.

Stiles is the only suspect on the list who does not work for the police, he had many problems with justice publicly revealed but there never was any official proof. I believe this is because he was protected by the criminal organization which covered more than the public list of crimes he was accused of, like killing  detractors of Visualize, or their relatives like in PJ's case.