Thanks to Kcit for an enjoyable and well constructed puzzle.
Before I file it away, can I just clear up one point:-
Is the 6 letter word that produces the T in the person's name produced by an alteration to the 4th letter in 19d to match "disfigured"?
By pure coincidence, earlier today I got the audiobook of Fermat's Last Theorem by Simon Singh which, obviously, is not a million miles away from this:-)