I have no personal data on this, but I feel when the wound happens and you are forced to continue the job and at times that means you either leave that fallen Brother with the Corpsman/Medic or at the medivac point for a pickup by helo or vehicle. This to me rips away a means of closure, normally we as humans like to be with loved ones at their time of death and after to make sure they are taken care of. When you are left with a injured Brother, and the last thing you know is person struggling to hang onto life simply fly away never to be seen or comforted as the slipped away it robs you of closure.
For me, when I was absent when the life slipped it left a mark. Especially if you were in charge of them or within their team as you always feel you should have been there to protect them. You are always left with the question, could I have done something! If I where there, could I have prevented your Brothers Death. This can be especially hard if you had close bonds before the events. Many times as Family, Brothers in Arms we always try to reassure the families which are by extension part of our family that we will be there for them and their loved one.
Again, from my own point of view, loosing a Close Brother or witnessing evil acts and death occur to a child are events that make the wound “Deep”. When I say “Deep” I mean it is an event that can never be lost from your memory you can only find a way to try dealing with it. I have lost much in my life as my father and many many people in my family passed when I was a child. In fact, I remember in grade school after my father died being asked a question by the school counselor when I returned. The question was simple, are you ok, I feel your pain? Can I help with anything? I never have thought of myself as a insightful person, but I remember telling the counselor “You can never understand my pain, you can only understand my suffering!” From what I recall of the talk, the Counselor cried and once they where composed again I returned to class.