It's certainly more likely that it's a cartel hit, but if it is related to CHAZ, I'd imagine it's them "cleaning up" after someone's mess. Maybe some organizer got too hopped up on LSD and meth and raped and killed a chick or a junkie ODing on fent.
Either way, they can't let their "peaceful movement" be stained by these incidents, so they watched a few episodes of Dexter to figure out how to saw up the body and dumped it in the lake. Then if someone asks questions, point a finger at the cartels or the nebulous "far-right groups" as the cause.
Since cops can't come in and do any forensics, the case will go cold and it'll eventually be forgotten. If you think bout it, it's pretty easy for them to dispose of unwanted or problematic people with little repercussions. Only problem is that the vast majority of them are prolly dumb leftists that would prolly fuck that up.