"No one comes home from war unchanged," says the Iraq and Afghanistan Veterans of America. And while those who have faced multiple deployments are the most likely candidates to lash out irrationally after returning, it's impossible to discount how the grind of an eight-year war has affected the rest of the military, who see friends leave whole and return in pieces; who wonder constantly if they'll be next. (As a psychiatrist, Hasan may have been particularly vulnerable: there have been numerous accounts of chaplains suffering from depression and PTSD after counseling returning soldiers. Hearing their horror stories, sharing their pain, and being unable to help often pushed these men over the edge. The fact that they were supposed to be healers, that they had never seen combat themselves, made it much harder to ask for help.)