Question about Retrograde amnesia and PTSD

I'm 2nd year psychology student and i have a case on which I am working and need help getting to the root of the problem regarding a PTSD victim whom served in the army and developed a delayed retrograde amnesia following events that happened to him almost 10 years ago and i need to know if it's possible at all that my patient lost the memories of the past 10 years of his life, only now after nearly 10 years had passed since the traumatic events that triggered the amnesia.

If it would help, I can provide some minimal information about the patient however I come up blank as to how to assess the information given to me by my professor in psychology. The patient is documented to have developed PTSD after his military service, however the amnesiac event occurred nearly 10 years after, 7 years after his discharge from the military, and it has wiped 10 years of his life.

physical examination shows no obvious chronic signs of any brain or vascular diseases (apart of very high Cholesterol levels, 3 times more than normal). Creatinine levels are normal, red blood cell count was a bit high, EEG results are normal, CAT brain scan shows some minor abnormalities but nothing that would suggest indefinite that the amnesia is linked directly to physical issues. Neurological examination and sleep lab tests show a very abnormal sleep disorder, as the patient is chronically insomniac, REM phase documented is 280 minutes, with numerous awakenings during the night. the patient is willing and cooperative with me, although unable to recall any memories from the past 10 years.. event occurred while being abroad and traveling on a train, he recalls waking up on a train thinking it was the year 2002 and not 2012, with no clue whatsoever about his whereabouts or doings in a foreign country. now, after nearly 5 months had passed since his amnesia developed, he has no recollection of the past 10 years of his life whatsoever. last memory he shares is a party that friends thrown for him before he was getting drafted into the military service.

i have to say that his previous record shows he attended a few sessions with a psychiatrist a year before the event, was diagnosed with PTSD and given medicine, MIRO, STILNOX and Ritalin L.
althou abruptly stopped taking the medicine and disconnected any touch with the psychiatrist, went abroad, returned a month ago and has been suffering from amnesia ever since..


could somebody please help me find the proper tools to diagnose him correctly so i could tend to him and help him overcome his issue? I have never heard about a retrograde amnesia developing on itself as a delayed episode in life.. as in this case. (subject had PTSD but was discharged nearly 6-7 years ago from the army,and althou PTSD was diagnosed, there were no sign of neurological or psychological disorders that would cause him to loose his memory, and if makes me believe that something triggered the amnesia as a direct impact on his memory, not surely related to PTSD, however as the memories impairment go as far as to the last week before he was drafted into the army, i could very well be wrong. please help me understand this issue a bit more as well as explain to me if there are any documented cases of people developing retrograde amnesia so late after the episodes occurred.. i mean.. its nearly 9 years since the last document of a battle he had in the army that caused him to develop PTSD, could it really be the cause of loosing all memory after nearly 9 years has passed since those events?