If you think that the GI you are searching for was killed during the war then you might want to check a couple of places. The first is the American Battle Monuments Commission
The names that are listed, (you have to type in the name), are only those who died overseas AND are buried overseas. If the body was returned to the USA then it will not be listed. Those personnel whose bodies were never recovered are listed.
They can also be contact at the following address:-
The American Battle Monuments Commission
Courthouse Plaza II
2300 Clarendon Boulevard
Arlington, VA 22201
Phone (703) 696-6900
Fax (703) 696-6666
If you phone ask for all the information they have on your relative and be sure to get his military service number. The Battle Monuments Commission will also tell you where he is buried and if you are the next-of-kin they will send you a photograph of the grave.
The National Archives list of casualties offers a list of casualties but you must know the state that the person called home.
How to Access W.W.II Casualty Lists on the National Archives Website
1) Access the National Archives website at: www.nara.gov
2) Click on The Research Room
3) Under "How to do Research at the NARA, "click on NAIL Database
4) Click on Search Archival Holdings
5) Click on NAIL Digital Copies Search
6) You will see two "Enter Keywords" boxes.
7) In the first box, type "War Casualties". In the second box type either "Army" (to access War Department lists) or "Navy".
8) Click on the "Submit Search" button at the top of the page.
9) You will see a form which contains "Hits Retrieved."
10) Click on the "Display Results" button at the top of the page.
11) You will see images of the covers of each State booklet.
12) Click on "View All Thumbnails" to see thumbnail images of all the pages for a particular state. Each thumbnail may be enlarged by clicking on that particular page or access file.
13) PLEASE NOTE: Because the images had to be enlarged so they could be read clearly, you cannot print an entire page.