Not a science fiction story. One of an unknown number of detective stories Silverberg wrote in the 50s, most of which were published under pseudonyms.
Other resources
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Acknowledgements: Robert Silverberg for cause, support, and cooperation; Ken Seamon for graphics; Rodney Walters for books and info; Alvaro Zinos-Amaro for comments and content; and all the fellow fans who have sent encouragement, information, and translations.