Sioux Ordnance Depot Fire & Guard Headquarters Sidney, Nebraska

I am the grandson of a certain Marvin K. Clark whose last known location was Sidney, Nebraska in 1946. He indicated in a letter he sent home to his wife in Oct of 1946 that he was working at an Ordnance Depot near Sidney, NE and that the project he was working on was what he referred to as a "cyclotron." I find no definition of "cyclotron" other than it being a particle accelerator used in nuclear research.

Evidently, my grandfather was a machinist/technician of some perhaps advanced sort. His home was actually in Endicott, NY, which is where his wife and 3 children lived, but during the war years he was sent to a variety of war-related industrial sites and jobs across more than a few western states; the last known of which was the Ordnance Depot at Sidney, NE. His wife and kids remained in NY. In Nov of '46 his wife, my grandmother, sent a letter to him in Pueblo, CO, but it was returned to her marked "Return to Sender" as if undeliverable for some unspecified reason, and nothing more was heard or seen of Marvin K. Clark after that. Why she attempted to contact him in Pueblo is not known since her wording in the letter indicates that she is not even sure if he is there. I have a collection of his letters (16 in all) that he sent home from a variety of locations in the western US. Included among them is a small collection of pay stubs (7 in all) which he received during a brief employment stint back home in Endicott, NY, late 1945 through early 1946, i.e., prior to his next appearing in Sidney, NE. His NY State-issued Soc Sec Number as it appears on his pay stubs returns no hits as being assigned to him..... it's as if his identity was erased after Oct 1946. Without a Death Certificate, the Soc Sec Administration is no help in shedding light on this puzzle.

In retrospect, Marvin Clark's disappearance by way of identity erasure makes sense since it is also a fact that his marriage to my grandmother was not a happy one. She was a rather vindictive and unyielding personality, and it is my belief that it was Marvin's fear that there was no other way of extricating himself from her aside from his completely disappearing. He was the perfect candidate for something like Los Alamos or Area 51 given his training and experience, and given also that he had a life and a marriage that I am convinced he wanted to lose.

I'm thinking (guessing) that maybe the cyclotron he mentioned in his last letter was, in whole or in part, fabricated at the Sioux Ordna