Just a reminder about the 'needs psychology' of post mass-murder narratives
There is a huge desire within society to create a narrative that simultaneously explains the event in a manner that increases our perception of safety of ourselves and makes such killer(s) seem distant and outside our own lives.
This very often involves the creative alienation of the killer(s) and assurances that psuedo-identifiers are useful in promoting our safety.
The dynamic of the narrative protects us from anxiety while making us vulnerable to mistaken presumptions.
The further members of threatened groups can push the narrative into acceptance the better/safer they, and we who adopt their narrative, feel.
The less dissonance we have to deal with in our thinking, and the clearer completely wrong answers appear. Broadly held misconceptions are seeming more applicable, reasonable and substantiated by antecdote and fantasy.
That's because as in all fiction, including post mass-shooting narratives, we suspend disbelief and critical thinking.
No, people, in a Venn diagram deviance is not a subset completely within mental illness. And you cannot diagnose psychosis caused by sugar addiction from the appearance of someone's eyes in an old photograph anymore than you can predict future homicidal tendency by the bumps on their head.