if you do a search on mass shooters on prescription meds, I came up with over 50 websites on it, here is one...
https://www.naturalnews.com/039752_mass_shootings_psychiatric_drugs_antidepressants.html#
Ross Pomeroy, Chief Editor of RealClearScience: "Natural News has possibly done more to popularize conspiracy-oriented and pseudoscientific beliefs than any other news outlet this century."
Now, here is information from a legitimate source (via the National Center for Biotechnology Information):
What is the scientific evidence for an association between psychotropic drugs and homicidal behavior? Most of the available studies are case reports that only suggest a coincidental link between violence or homicide and antidepressants or benzodiazepines, while very little is known about the association between antipsychotics and homicide. Two recent ecological studies found no support for a significant role of antidepressant use in lethal violence in the Netherlands or the U.S., although data on individual offenders were not available. Quantitative data from the U.S. Food and Drug Administration (FDA) adverse event reporting system imply that some antidepressants may be associated with a disproportionately high number of violent events. On the contrary, two small studies on antidepressant use among a special subgroup of homicide-suicide offenders found no evidence to support a causal link between antidepressants and homicidal behavior.
There are three crucial conditions that must be fulfilled to properly study the putative association between exposure (i.e., use of a psychotropic drug) and outcome (homicide): a) the sample must be unselected, to be representative of the total offender population; b) the reason for prescribing the medication must be considered and controlled, and c) the effect of other concomitant medication(s) must be adjusted. No such studies have been done thus far on the association between the risk of committing homicide and the use of psychotropic drugs.
There are three crucial conditions that must be fulfilled to properly study the putative association between exposure (i.e., use of a psychotropic drug) and outcome (homicide): a) the sample must be unselected, to be representative of the total offender population; b) the reason for prescribing the medication must be considered and controlled, and c) the effect of other concomitant medication(s) must be adjusted. No such studies have been done thus far on the association between the risk of committing homicide and the use of psychotropic drugs.
Quote Source:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4471985/