On the below link, if I am translating the Russian correctly, is a purported photo of Willi in captivity.
Also, I do not believe he died but did survive the war (or atleast as to the following story could not have died in captivity...unless the dies in captivity refers to being recaptured by the Soviets in '45). He is the JG5 pilot who was shot down and captured, then supposedly indoctrinated into Soviet ideology and sent back over the German lines. He was picked up by the Germans and after interrogation and having his identity verified by Horst Carganico wasn't allowed to fly combat, but went to a training school.
The above is as per Girbig's JG5 book.
Post #21
http://reibert.info/threads/%D0%9B%D...2%D0%BE.79949/