This is just plain irresponsible journalism
SSRI (Selective Seratonin Reuptake Inhibitor) antidepressants have been shown to be present in the bloodstreams of depressed suicides in a disproportate number of cases. The reason is not difficult to figure out: these drugs- which do nothing more or less than restore a normal level of serotonin to the brains of those taking them- relieve the inertia which characterizes depression before they removes the emotional pain which motivates suicide. There is therefore a window in which it becomes possible for depressed patients to act on suicidal ideation which was there all along.
But there is no evidence at all that SSRI's cause such ideation- and there is certainly no evidence that they cause violence toward others. The only possible way in which SSRI's could be involved in the Charleston case would be if a murderously disturbed individual had only been inhibited from committing murder before because he was depressed.
The number of lives that have been saved- the number of suicides that have been prevented by SSRI's- are to the number of deaths in which they may be even so indirectly implicated as a glass of water is the Pacific Ocean.