Photographer and the Final Payment

In the February 24, 1982 issue of Ellery Queen''s Mystery Magazine, the editor offered the following challenge to the Author: "A plot idea for the next Photographer story: when Manuel looks at the name and address on the slip of paper handed to him by Rodolfo, he reads his own name and address. He has been given the assignment to nullify himself! How does the Photographer give positive proof to th...