It's always called a mental thing by the media, when White's commit massacres.
Unlike others - I think this is a good question with a very easily-observed state in the media.
It's ignorance
about mental illness that drives this forward.
We're used to associating mental illness with violence
IF the perpetrator is 'withdrawn from society' maybe a 'recluse' and 'secretly plotting' while they remain 'quiet'.
Being withdrawn from society, quiet, secretly paranoid, 'weird' - People associate THESE 'anti-social' behaviors with mental illness (while overlooking OTHER behaviors that are related to mental illness'). - these are NOT prevalent in various cultures and values that comprise the black community generally speaking.
And so you get this tired and worn out stupidity: He was such a nice guy. (See - being 'nice' overshadows the concept that you're 'mentally ill' or 'simply a time bomb waiting to go off') She was a good mom, I had no idea she'd go off and kill her children. (Because hating children is such a normal thing these days)
People tend to see African Americans as head-strong, solid, and level . . . with just a heavy
occasional dose of an attitude problem. (Note how a lot of people who have a heavy dose of an attitude problem are NOT seen - no matter what the race - as being mentally Ill. People don't want to write off 'violently angry' as a mental illness - ever)
Now - I'm from a biracial family . . . and I'm an author . . . so my exposure to things is very different in a strange blend sort of way. Last year a very interesting writing-thread popped up at another community that explains how differently personalities are seen (and not necessarily in a 'racist' sort of way with the intention of being negative or demeaning). This comment here (and I write romance/erotica - so that's what this was about): Why is it that all bdsm stories have white shy women? Why not a robust black woman that just want to be taken and dominated? (and she went on to refer to herself - etc).
And it opened up a huge discussion on racial stereotypes in writing - and in real life - and it was all very interesting.
People simply COULD NOT wrap their minds around a confident, self assured, outgoing, strong-willed female wanting to be dominated OR black male and female dom/sub concepts in general.
I guess it just pushed the reality-button too far gone?
I found it funny - and engaging - and that's what your thread made me think of. White = shy and quiet / possibly off kilter but overall easy to overlook. Black = bold and confident / this is what gets them 'in trouble', in fact. [When people make assumptions and function by default, these are the defaults]
Now white people who are bold, outgoing, daring, vibrant are ALSO assumed to be mentally balanced. This is associated with 'happy' and 'content' with life, not associate with mental instability.
This, in fact, sums up the issues I've had with my son RE his mental illness. People didn't SEE he was mentally ill because he was HAPPY and OUTGOING and just mildly annoying - even though those were symptoms.