Go Blue! Wallenberg was a Michigan alumnus.
It’s possible that Wallenberg survived until the 1960s or even later, in a Soviet camp.
The problem was, the Soviets didn’t want to admit it, and it was likely Brezhnev’s political detachment of the Red Army that seized him in 1945 (hence the need to keep that quiet).
If so, he languished in the Gulag because the US and the West didn’t want to upset the applecart of good feelings with the Russians over a single man.