Getting on drugs and becoming schizoid after is pure fault of the one getting on drugs, because drug addiction consequences are known to everyone including R/R drummers from LONG time ago.
Killing mother under influence of drugs or alcohol or consequential influence of schizophrenia is definitely punishable offense. Drugs or even drug dealers aren't guilty at all. The guilty one is whoever abused them to the point of psychological instability. Fortunately he was locked up and bothered no one with his occasional schizoid aggressions.