I reckon that the CIA has infultrated his house, stolen Dann and is trying to make it look as though he never existed.
Yes, Dann uncovered secret proof of the shape of the Earth and they took him away!
We can only guess what knowledge Dann uncovered, and what the true shape of the Earth is. We shall be forever stuck with FE and RE, both sides arguing blindly over ignorant theories while Dann laughs at us from above, basking in the bliss of true knowledge.
Alas.