The senior officers generally tried to keep as accurate a record as possible of the names and places of burial. These greatly assisted the search teams. Some POWs volunteered to stay on and assist in this process. In the book RAILWAY MAN, we learn that even one of the KempeiTai translators volunteered to assist in this effort and was greatly affected by the experience.
Here are a few examples of the photos of that search and maps that the POWs managed to keep as to the whereabouts of the burial sites:
While thousands of the Australian, British and Dutch POWs lie buried in the 3 CWGC cemeteries, all the remains of the US POWs were repatriated to their families by 1948.
Documentation of the graves search by the Australian search teams: