Raoul Wallenberg's half-brother, Guy von Dardel, a well-known physicist, retired from CERN and dedicated the rest of his life to finding out his half-brother's fate. He traveled to the Soviet Union about fifty times for discussions and research, including an examination of the Vladimir prison records. Over the years, Professor von Dardel compiled a 50,000-page archive of interviews, journal articles, letters, and other documents related to his quest. In 1991, Dardel initiated a Swedish-Russian working group to search eleven separate military and government archives from the former Soviet Union for information about Wallenberg's fate, but the group was not able to find useful information. Many, including Professor von Dardel and his daughters, Louise and Marie, do not accept the various versions of Wallenberg's death. They continue to request that the archives in Russia, Sweden, and Hungary become available to impartial researchers.