All you have to do is search the web for "antidepressants and violence" to see several articles written about this subject.  Take someone who is disturbed, put them on medication with violent side effects and turn them loose with anything and they will likely do harm.  My heart goes out to the people who were shot in Lousiana.

Here's a list of 35 other instances of violence committed by people on psych drugs if you need more convincing.