conduct a study to determine the relationship between medically prescribed psychotropic drugs and mass killings.

It has been reported that the killers in many recent mass murders were taking medically prescribed psychotropic drugs. See here; http://www.cchrint.org/school-shooters/
The government should conduct a study to determine the relationship between medically prescribed psychotropic drugs and mass killings. In particular the study should determine the percentage of the killers who were taking such drugs and compare that to the percentage of people in the general population who are taking these drugs.