SSRIs can have entirely different effects on people. Setraline for example at the same dosage can help one person, drive another to commit suicide, or do absolutely nothing for someone. Literally they just play around with dosage/SSRIs until the patient reports that it's actually helping. And sometimes SSRIs that seem to have worked for someone for years suddenly don't help anymore. There's really no easy way to treat someone like that guy. But an SSRI could have definitely played a role in pushing him to do what he did.