Amy, while the link between the killers and the medications they were on is uncertain, it is a weak analogy to compare these medications to water. Is there research showing that people who drink ordinary tap water become agitated, violent, or psychopathic? Not that I know of, but I do know there is some research showing that in a percentage of people, medications can cause those effects.

For example, as described in the article "Antidepressants Increase the Risk of Suicide and Violence at All Ages" by Peter Gøtzsche, MD.

https://www.madinamerica.com/2016/11/antidepressants-increase-risk-suicide-violence-ages/