After immigrants are detained by ICE, there are probably records somewhere of who has an attorney, and who is calling family members or an attorney.
For the immigrants who aren’t calling any family or lawyers, the poorest of the poor, people with little to no connection to anyone, who may not even say which country they are from, if the administration were actually trying to kill as many disconnected immigrants as possible in secret, would society know?
For example, if the administration was composed of all types of conservative people, but 30 percent were secretly Nazis or wanted racial genocide, could there be a campaign to not just remove, but kill, immigrants, and the public doesn’t find out?
I’m not sure that your second point is still a constant, though this is just an opinion and I’m open to discussion on this. They seem to have solved the problem of people not being up to mass killings, through desensitization through social media (I’m thinking of telegram groups specifically). There have been a lot of cases shown recently of people taking outright glee in their and others’ grotesque murders, en masse.
Actually this is pretty good evidence they haven’t started doing that yet. There would be leaks.
to add to this point, they have driven cars through protestors and approved of people doing so.