Probably a graduation photo from boot camp or SOI. And marines don't wear CIBs; the corps isn't really into "tinsel" of any kind. I see your point, but he left the USMC as a corporal. So until I see a photo of him with two stripes, I'm not going to denigrate any combat service he might have picked up later. Regardless, I know a lot of people (not all of them SMs) with PTSD. It's not a terribly strong predictor of violent homicide.
NOR AM I re: any prior combat exposure. If combat PTSD was a predictor of violence there wouldn't be a human being left on earth especially after the Vietnam when millions of combat troops came home to the sound of one hand clapping. It's interesting most of the violence was directed at the VA's & hospital. PTSD was rediscovered in DSM-IV when it came out in 1989 IIRC