Researchers say new evidence from Russian archives suggests that a Swedish diplomat credited with rescuing thousands of Hungarian Jews from the Holocaust was alive after the Soviets reported his death in prison.

The fate of Raoul Wallenberg, whom the Soviet army arrested in Budapest in January 1945, has remained one of the great mysteries of World War II.

The Soviets claimed he was executed in 1947 but never produced a reliable death certificate or his remains. Witnesses claim he was seen in Soviet prisons or labor camps many years later.