WC: Those are all high-control CULTS. So yeah, I'd say if you were raised in any of them chances are you are messed up mentally in some way, shape, or form. So therefore relevant.
I agree. The shooter's JW upbringing is relevant. It is not the only factor that led to his behavior but I do think that it is a contributing factor.
JWs are indoctrinated into a "us verus them" mentality and are told that "worldy" people are not to be trusted. This man was raised, by the accounts that I have read, in a so-called devout JW family. He would have been exposed to that "us vs. them" mentality from the time he was a baby. This type of thinking cannot always be changed, and in this case, it obviously wasn't - the shooter revealed that he still had the residues of JW ideology when he spoke about "Jehovah".
Regardless of his mental state, the JW ideas that had been planted in his brain about the world being an untrustworthy place would have had great bearing on how he coped with his problems, whatever those problems were.
Some people can undo the persecution complex that the JWs are so good at giving to their members - some people can't.
We will never know the nature of his mental illness or whether he had a diagnosable personality disorder such as being a psychopath, but the JW ideas that he was exposed to as a child growing up would have led to the "perfect storm" that unleashed itself in the form of violent behavior.
The JW ideology is very good at disempowering people, and in this case, with deadly results. This fellow chose to empower himself by killing other people.