I can't say anything for sure. I am not too familiar with drug use. It's totally possible that something happened because of this.

I have autism too, but I can say that sometimes people with autism say things because they hear it from a favourite movie or TV show or a person they idol. For me, I used to say the same phrase from a TV show over and over again. My stepbrother copies what my dad says because he really likes my dad and his own dad isn't a good person.

Looking up about shootings is an interesting topic, but people with autism may have a special interest. For me, which I do, I am really interested in learning about mental illnesses. Topics vary of course.

Tics are common. Normally, people with autism call it stimming. Like, sometime I will shake my hands for no reason, or I will rock.

Aggression is also common among autism. Some people with autism go on medication to help manage the aggression levels. It is not okay to sexually assault anyone though, and it should be reported. That is not part of autism.

Most of it is a part of autism, just not really appropriate though. Is it possible that the people he's been hanging with are not a positive influence, like when he was doing drugs? This could influence the change in interests and sayings.

Hope this helps.