That's the world they live in. They form a preconceived notion based on their own prejudices and political desires, build a narrative around it, repeat it over and over until it becomes "fact" in their minds, slap a coat of quick-dry varnish on it and pronounce it gospel. And no amount of reasoning or evidence to the contrary this side of Hell is going to dissuade them. They'll use every psychological defense mechanism in the book to prevent their little fantasy from crumbling, so emotionally invested in it they are. We see it to one degree or another over there every day.
Take for instance the meme that "the police ordered Zimmerman not to follow Martin". It doesn't matter how many times they are corrected, the correct quotes provided, the call transcript linked to, etc., in the very next post you'll see someone state it again, as if they didn't even see the evidence to the contrary posted there and in a hundred other threads. It's the same thing as in the Duke rape case. There was practically zero objectivity. It wouldn't surprise me if there were DUmmies that stayed in bed for days in a darkened room sucking their thumbs after the truth of that one came out, so fragile are their psyches.