In his article on Claude Degler in Fanstuff #25 (page 6), Arnie Katz writes:
Jack Speer, a lawyer and judge, went to Degler's adopted home town
and researched Claude Degler's claims. His Investigation in Newcastle presents a comprehensive case against Degler. It exposed most of the people, places and events he had written and talked about as a mixture of
extreme distortion, delusion and outright fantasy.
Investigation in Newcastle put the nail in the coffin. Degler tried to
inch back into Fandom under a couple of different pseudonyms. Lightning didn't strike twice for him and he faded from view.
Courtesy of Robert Lichtman, here is Investigation in Newcastle: