Your comment prompted me to go searching, and I found this:

http://www.smh.com.au/federal-politics/political-news/missin...

The claim is that Wallenberg was sighted within the Soviet detention system up until the 1980s!

There has always been speculation that Wallenberg was alive and kept locked up somewhere. My dad has been trying to find out what's happened for years and years. The honorary Australian citizenship was a really important event in my fathers life.