This is a detective story I have not seen listed in any bibliography, one of who knows how many non-SF Silverberg publications from the time.
Other resources
(None on file)
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.