I read in another article that his parents had him on a significant amount of meds while he was in school. Of course the articles that DP reprints are very incomplete compared to other articles out there.  This domestic situation involved his mother in law.  Have not heard what it was about.  But he made threatening comments in texts to her, so she had some idea that he was enraged.  Also, of course not in any DP article, the guy who went after the shooter actually shot him and while the shooter was driving, he called his dad and said that he was shot and probably wouldn't make it.