Your examples don't stand up.
"If, for example, someone found a dead Marxist professor killed within a stone's throw of your home and four of his young students were missing* and suddenly the police review your posts here and put you as the most likely suspect"
I didn't say torture a "likely suspect", I said someone known to have done it. Had cameras taken pictures of Tom walking up to, talking with, then grabbing the victims' arms and leading them off, and had hair and blood samples of the victims been found in Tom's car, I'd say Tom would be in need of some serious "persuasion" to tell the whereabouts of the missing students. Contrary to what some believe, there comes a point where the evidence is so conclusive and damning, that a verdict of guilt can be rendered within seconds. And if someone's life is at stake, that verdict should be enforced with extreme prejudice.