There's a similar tendency I've noticed with these, where people who have met or interacted with the person pile on with vague statements. This is a popular one: "I met him once and knew something was off! He had a creepy vibe".
I'm sure it reflects their interaction in some cases, but it's so common with these witch hunts (including the one in question here), there may be more to it. Motivated reasoning or something?
Some of the more specific ones could be ex-post re-rationalizing. Like when someone discovers their neighbor was a crook, suddenly his or her demeanor in retrospect was suspicious, or had wide eyes or had eyes close together, said hi but said it fast, or never said hi, or something whatever it is that sets them apart from non crooks.
It’s often clear they’re just taking a birdshit on something that looks like it can earn them internet kudos.
Dynamically it doesn’t seem far removed from a lynchmob.