Fifty-three percent of the would-be bombers showed “depressive tendencies”—melancholy, low energy, tearfulness, the study found—whereas 21 percent of the organizers exhibited the same. Furthermore, 40 percent of the would-be suicide bombers expressed suicidal tendencies; one talked openly of slitting his wrists after his father died. But the study found that none of the terrorist organizers were suicidal. The paper was published last year in the journal Terrorism and Political Violence.