Why are we so obsessed with John Demjanjuk?

On Tuesday, the United States Holocaust Memorial Museum released a photo of Sobibor guards that purports to reveal Nazi collaborator John Demjanjuk in a guard uniform at the Sobibor Death Camp. German historian Martin Clippers said the museum used the German police to conduct a biometric examination to affirm it was Demjanjuk.
I have seen the picture and it may well be him. But this photo is not what proves that Demjanjuk was at Sobibor. It is the overwhelming amount of documentary evidence f…