In physics there is this famous history facts about Ettore Majorana, brilliant student of Enrico Fermi that predicted the neutron and developed the idea of Majorana fermions, that suddenly disappeared. Are there similar disappearance stories in the history of mathematicians?
There are some other examples of physicists and mathematicians disappeared after Majorana.
Vladimir Alexandrov disappeared in 1985 at 47. He created a mathematical model for the nuclear winter theory and the circumstances of his disappearance have never been clarified (maybe they were related to his work).
Boris Weisfeiler was a US algebrist who disappeared in Chile in 1985; it is possible that for some unknown reason he was seized by a Chilean army patrol and taken into a secretive Germanic agricultural commune and then killed.
Aleksandr Khazanov was a PhD student and a child prodigy, one of the youngest to get perfect scores at an International Mathematical Olympiad. Despite his young age (he disappeared in 2001 at 20), he authored a paper on a variant of Fermat's Last Theorem.
Paul Tseng was a professor in applied mathematics (he was a major researcher in optimization). He disappeared in 2009 at 50 while kayaking in the Yantze, and probably died.
Ph.D. Univ. Michigan, 1967
specialty: complex analysis
Prize-winning dissertation, his advisor Alan Shields called it the best thesis he had ever directed.
1968, appointed Assistant Professor at Berkeley
Resigned suddenly, June 30, 1969.
Disappeared. Not seen for more than 25 years.
We now know he spent many years "off the grid" in a remote cabin in Montana that he built himself.
From 1978 to 1995 he carried out a series of bombings, becoming known as the "Unabomber".
Arrested, April 3, 1996.