No way cops will misuse technology, right? 
And then claiming it's a real person who'll get thrown in jail.
Putting on my evil cap... if they do this the "smart" way they'd make absolutely 100% sure that if they employ this type of technique and it ends in convictions that they get a 100% guilty beyond any doubt type guy. And do that a bunch of times. Probably a minimum of a dozen times, but the more the better. Conservatives are unlikely to give any shits as long as they make sure anyone convicted isn't white. And liberals will fatalistically accept that although they aren't fans of it... look at the results!
They've already been basically doing that for years now against DNA profiling from those ancestry databases. If you bring up the fact that this is all dystopian and, honestly, kind of unnecessary you get hit with "but they caught [insert terrible person who did terrible things]. Why do you support [terrible things]?" Just more copaganda bullshit from liberals. It catches everyone with a conscience because, yeah, sure catching some rapists from the 80s is good. No one will say it isn't. That doesn't alleviate the current moral concerns though and the fact that everyone basically universally agrees that states like the US federal government are definitely not "good." People will have different reasons for that belief, but I hardly ever ie never hear anyone say the gov is good or benevolent. So... why would you willingly give that group more power of this type? More police powers, more war power and such. I mean, assuming you COULD stop it, which is unlikely since there's no real collective movements in the US, why wouldn't you? I guess the assumption is the power will always be used to punish your "enemies" and maybe sometimes people you sympathize with, but certainly you yourself. So, fuck it.
If authorities abuse this type of stuff "correctly" it'll cause nearly zero pushback and once it's accepted as normal they can use it for anything they want. Not that this is even necessary to control or manipulate populations.
I haven't really fully thought it all the way out, but one of the more successful ideological turns (for fascist-minded types) that has emerged from the circa pre-1980/90s era right wingers who also would have voiced concerns about this type of stuff (think Alex Jones but not so full of shit- which is what Alex Jones used to be) is getting them all to NOT be opposed ideologically, morally, politically, whatever to things such as the patriot act. I'm just barely old enough that I remember the fiery debates online and off about the passage of that act. It was incredibly unpopular even then and has remained like fucking... near zero popularity except among the most authoritarian of the authoritarian right wingers and maybe some racist, scared liberals convinced the NSA won't look at their dick pics. Yet it passed, and the right wing never says shit, liberals won't say shit since they're ideologically bankrupt and spineless, and the left has no power.
In all that rambling I think I'm just observing that people have fully come to terms with reality, they aren't willing to organize and do what's necessary to make this not happen, and we're all fucked. Somehow my conclusion is always we're fucked... fuck.
I almost feel like the feds or police departments hold onto some cases that are already solved for a few decades to use for some new ghoulish shit like this as an easy win in the eyes of the masses. Like there's no way they hadn't already figured out EARONS by 2001 when they figured out it was one dude. It's insane that it took a fib about a floppy disk in 2005 to figure out BTK.
There's no way nobody has ever figured out DB Cooper or the Zodiac killer. Like, all of these long-after cold case busts with some new controversial tech always end up being some dude the cops already suspected but didn't basically just turn himself in so they stopped caring, or that they had explicitly ruled out at the beginning based on some flaky evidence that turns out to be so obviously wrong it's suspicious. Like there's no way they aren't giving up that easily on purpose.
